電子線手法を用いた炭素の観察(<特集>地球における炭素の循環)

(1)

電子線手法を用いた炭素の観察(<特集>地球における炭素の循環)

著者田崎和江

著者別表示 Tazaki Kazue

journal or

publication title

Earth Science

volume 48

number 4

page range 395‑412

year 1994‑07‑25

URL http://doi.org/10.24517/00061678

doi: 10.15080/agcjchikyukagaku.48.4_395

Creative Commons : 表示 ‑ 非営利 ‑ 改変禁止

(2)

The Association for the Geological Collaboration in Japan (AGCJ)

NII-Electronic Library Service

The Association for theGeological Collaboration in Japan{AGCJ)

EARTH SCIENCE (CHIKYU ^KAGAKU)

Vol.4B, No.4,

_pp,395-411

July ¹⁹⁹⁴

395 Observation ^of carbonbyelectron microtechniques

KazueTazaki*

Abstract Very fine

carbon

particulates formed by both inorganic

and

biological processes in the Earth have the

most sensitive response

to global

^change,

Various

electron microtechni-

ques

^are ^usufu1

^to

^reveal

^the

micromorphology,

texture, growing processes,

crystalinity, chemical

bond

^and

the distribution

^of ^carbon ^materials.

^In ^this

^article ^usefu1 ^methods

^for

evaluation ofcarbon

in

various carbon materials are

introduced. Amorphous

organic ^carbon naturally and artificially

transfbrms into high

crystalline

graphite. SEM

and

TEM

observa-

tions

revea]

that precursor

^carbon ^materials ^are ^composed ^of ^spherules,

^tubular, fiakes, thin films, flat

sheets, and ribbon texture.

Bacteria

and nannobacteria may

play

^a

prorninent

catalyzing role

in the precipitation

^of ^carbon ^materia]s.

Hexagonal

onion-like

texture is the

most stable

form

^ofcarbon

during graphitization, EPMA

and

Auger

can

be

^used

for

carbon elernentary rnapping.

Auger-spectrometer depth profiling

^and ^carbon ^content ^rnap ^applied ^to

Sybille Monzosyenite having high

^electrical conductivity revealed a

high

concentration

of

carbon on

grain boundaries

of

the

minerals.

Chemical bonding

of carbon and

hydrogen

can

be

anaiyzed

by FT-IR

method.

FT-IR

^spectra ^showing

^different ^intensity

^of

OH

and

C-C

absorbed

bands

are related with the

degree

of crystalinity of

graphite in

rocks.

The

resu]t suggests that

graphite

^occurred

by dehydration

and reduction oforganic materials,

ESCA is

usufu1 method

to know

various carbon

binding, ^High

^resolution ^of

Cis

spectra of micro

ESCA

can

discriminate

various carbon chemical

binding,

such as

COO, C-O, C-C,

and

graphite, ESCA

spectra of

glauconite in deep

sea sediments showed various ratios of

COO,

C-O, C-C

^and

graphite,

suggesting organic origin of

glauconite. The

result also suggests

that there

are no clear

boundary between

erganic and

inerganic carbon . RILAC

method can

be

used

for

evaluation of atmospheric centamination of carbon

from

structural carbon,

RILAC

spectra of soot showed characteristic recoiled carbon, oxygen and

hydrogen ions with

standards of

purity for

metalic

plate

^and

Si02.

Key

wortZs :carbon,

graphite, bacteria,SEM,TEM, Auger, FTmlR, ESCA, RILAC.

I Introduction

What is

a

Global Carbon Cycle ?

Carbon is

a very useful

and

^applicable materials.

Because

carbon

fibers

maintain

their mechanical properties ^to temperatures

higher than any

^other ^material

in the Earth

(Hoffman, ^1992). ^The

^carbon ^atom, ^with

^its

ability

to be

^stable

ⁱⁿ

^a ^nurnber ^of

different

oxidation states

(-4 ^to ⁺⁴⁾

^and

^its ^tendency

to form stable

^covalent

bonds, is

^very ^efficient

at

storing

^and ^releasing ^energy.

In

natural

Received December 28, 1993;

accepted

April

Z8,

1994

.

Department

of

Earth Sciences, Faculty

of

Science, Kanazawa University,

^Kakuma,

Kanazawa, 920-11 Japan

(121)

(3)

396 Kazue Tazaki

systems, carbon appears

to

exist

in two princi- pal forms: (1) C02 trapped in the

mineral struc-

ture

and

(2)

^organic ^matter

ⁱⁿ ^the

environment.

They

âre ^relatively êpen ôr/and ^closed

to

mixing with

COz from the Earth's

atmosphere

(Yapp

^and

Poths, 1986). The biochemical

mechanisms and

pathways that

control

the

flow

^of ^energy

through

oxidation

-

_reduction

reactions

involving

carbon are

known

as

the global

carboncycle

(Chapelle, ^1993). The

^ecar-

bon

cycle'

is generally taken to

refer

to the

Earth's

atmosphere, which contains about

750 billion tonnes

of carbon.

But geologists

^see ^a

far larger

carbon

cycle - the

carbon

locked

up

in carbonate

^minerals

in

upper crustal rocks

is

estimated

to be 7.5

×

10i` tonnes. An impor- tant question is

whether

significant

amounts of

carbonate are returned into the

mantle

by

subductien

(Green,

^et ^al.,

^l993). ^Weathering

produced

^a

total

of

2-4

^×

1025 g

^of ^carbon-

ates, clay minerals and

Si02 (ohert

^and

quartz)

in

approximately equal

proportions during the history

of

the Earth (van ^Groos, ^1988). ^It

^will

be

^noted

for the

carbon cycle

that the present

increase in the

atmospheric component

(0.4 %

per year) is

^normally ^attributed

to fossil fuel

combustion which makes up only

3 %

^of

^the

flux into the

atmosphere

(Fyfe, ^1987, ^1992).

The

research agenda

for the global

^carbon

cycle

is dominated by the _question

of

the

^'miss-

ing earbon'

^and ^sinks ^of

C02. ^There

are remarkable

tendency in the distribution

^and

chemical characteristics

of

humus in

soil.

The highest

organic carbon concentrations

in top

soils

gradually decrease

with

increasing depth

(Sheuji,

^et ^ag.,

^1993). ^In

^addition

bic)mineraliza- tion processes play

^a

dominant

role

in

sedi- mentary mineral

formation

and

C02 fixation

(Tazaki

^and

^Fyfe, ^1992; ^Folk, ^1993), ^The CO

or

CO2 is the

most

probable

^source ^oi ^carbon

graphite

^which ^are ^considered

^to be

efficient scavengers of organometallic compounds.

This

^make

them

suitable

for the fixation

^of

bacterial life in the

vicinity of

hydrothermal

vents,

(122)

How does carbon change to graphite ?

Graphite is

a common carbonic

phase in

a variety of supracrustal rocks metamorphosed

under a range of

pressure-temperature

^condi-

tions

and

has _proved to be a

valuable

indicator

of

fluid

movements.

Santosh

and

Wada (1993)

have provided ^the first

unambiguous

insight

into _graphite precipitation from COz -

_rich

fluids. Precursor

carbon material

or puorly graphitized ^carbon formed during

^a

transient thermal

event which

is

most

likely flash-

heating during

micrometeoroid

deeeleration in

the Earth's

atrnosphere

(Rietmeijer, ^1992).

Graphite is the

stable,

thermodynamic

equilib-

rium crystalline

form

of

the

solid element

carbon at ordinary

pressures. However,

^car-

bpn

can and

does

exist metastably

in

other crystallographically erdered

forms,

and

in a

wide range of

disordered

or

imperfectly

ordered structures.

On heating to

elevated

tempera- tures,

all carbons

tend to

evolve

toward the

ordered, equilibrium

structure of graphite by

the process

^of

graphitization (Fischbach, ^1970).

Jedwab

^and

^Boulegue (1984)

^recovered

^crystals

of

graphite

^with

antimonide

overgrowths.

This _graphite is

considered

to be of h},drother-

mal origin

; it

can readily

be distinguished

from

continentally-derived carbonaceous

par- ticles. Hydrothermal

experiments were carried out

to

synthesize

graphite from bitumi-

nous coal at water vapor

pressure

^of

O.5 - 5

kbar

using

1 % ^Li2CO,

^or

² % ^Ni

^metal ^as ^a

catalyst at about

320 'C - 405 =C

(Tagiri

^and

Oba, ^1986). ^In

natural systems,

graphitization

depends

^on metamorphic

temperature

and oxygen

fugacity, but

not on metarriorphic

pressure to

a

great

^extent

(Tagiri

^and

Oba, 1986).

How can

we

evaluate

carbon materials

? Electron

microtechniques are considered so significant and are expanded

by

study of variety carbon･

in

micron-order-seiected area of

individual _particle. In

an

inert

atmosphere

it

(4)

Observutien

ef

condenses

to form hollo",,

spheroidal

fulleren-

ces.

Carbon depesited

^on

the hot tip

^of

^the

cathode of

the

arc-discharge apparatus used

for bulk fullerene

synthesis will

form

nested

graphitic tubes

and

polyhedral particles. Elec-

tren irradiation

of

these

nanotubes and

polyhe- dra t,ransforms them into

nearly spherical carbon ^tOnion'

<Ugarte, ¹⁹⁹² ; Kroto, 1992 ;

Bethune

et al.,

1993). The

scanning

tunneling

microscope

(STM) ^images

^show

^that ^the giant

fullerenes

are ^roughly spherical

in _shape

arid

range

in diameter from

approximately

1 to 2

nanometers, corresponding

to fullerences

containing

60 to 330

atoms

(Lainb,

^et ^al.,

^1992).

Carb(}n

nanotubes are expected

to have

^a ^wide

variety of

interesting properties. The

sy･n-

thetic

single-shell

tubes

^with

diameters

^of

about

one

^nanometre

gro"T in the gas phase

(Iijima, 1991;Iijima

and

rchihashi, l993). In this

study useful methods.for evaluation of carbon are

intreduced inte

various carbon materials.

The

changing

proce$ses from bio- logical

organic carbon

to

mineralogical

in-

organic carbon are revealed

,by

various elec-

tron

microtechniques,

In

^order

to better

understand

the properties

^of ^carbon ^and

^graph-

ite, it is

^necessary

to

observe

the

crystallogra-

o

phic

^structure ^on

"m

^and

A

scale.

The

usuful electron microtechiques available

for carbon

work are

described in this paper.

II Experimentalmethodsandresults

FoHowing

^electron microtechniques were employed

for the

evaluation ^of ^various carbon materials.

First,

mineralogical

components

^of carbon materials are

detected by ^X-ray pow-

der diffraction. ^Perfect graphite

^show･s ^strung

o

peak at 3.354 ^A d-spacing

^whereas ^a ^very

disordered

^earbon ^shoivs ^weak

peak

^at

>

/1/3.44

A.

carben bs,electron mTcrotecnniques

11-1 SEM

SEOvr technique

^reveals inicromorphology and

the distributien of carbon

^materials.

Bulk

carbon and

graphite in

metamorphic rocks(123)

-･- ₃₉₇

from different three places (Dissanayake,

1981) (to ^be published

^about

these samples in

separate

paper )

âre ^mounted ôn â ^sample

^stub

with

double-sidcd tape

and coated with

Au for

SEM

^using ^a

JEOL JSM-T220A instrument

operating at

20 kV.

SEM photographs

^of

graphitc in

metamor-

phic

^rocks

from different _places

show variety of morphology w{th w･ide range of

textures, depending

on

the

crystallinity

(Figs. ¹

^and

^2).

IIexagonal platy grain

^appears

^most ^stable

high

crystalline

graphite (Figs. ¹ ^A, ^B

^and

^Fig.

2C),

whereas

flaky

^and

tubular _grain

seem

to

be low

crystallinity

(Figs. ^IC ^and ^1D, ^Fig. ^2A).

Low･-magnification

^view ^of

^the

^radiating ^nee-

dles

are closely

packed

^spheres ^of

5-IO _"m ⁱⁿ diameter. Homogeneous granular deposits

completely cover

the grain

^suggesting

poorly

crystallized carbon on

the

surface

(Figs. ^IA

and

2A). Well-crystallized typlcal graphite

shows

booklet f pyramidal

^aggregate,

2 - 10ptm in diameter (Figs. ^2C). ^Abundant

^small

spheres,

e.2 ^- 1 _ptm in diameter,

^were

common-

ly

observed on

the platy graphite

^as ^shown

in

Figs. 2B

and

D,

suggesting urganic origin of

carbc)n. The _spheres

are

found

not only

in the tow･-grade

metamorphic rocks

but

also

in the high-grade

metamorphic rocks, after

hydro fluoric acid treatinent (Fig. ^2D). ^The

^small

spheres

^can

be

called ^t' nannobacteria", about

0.03 - O.3 ptm in diameter, by Folk (1993), ^In

^all

cases, the carbonaceous,

^silicious ^and ^carbon

matters

partly

^and

gradually

^changed

its

morphology and

texture during graphitization.

The

crystallization

processes

^are ^related

^to the

morphology and

the

metamorphic

grade

which agreed with

TEM, ^XRD, ^FT-IR

^and

micro-ESCA results, as merition

belovv.

11-2 TEM

TEM techn{que

^reveals ^not ^only ^micromor-

phology, but

^also ^cr},stal

growth

^and crystalinity of carbon material$.

The < 2 - ptm fraction

^of ^carbon

^black

^standard ^sample,

green

^spherical ^materials

(glauconite) ^from

(5)

The Association for theGeological Collaboration in Japan {AGCJ)

398 Kazue Tazaki

Fig. 1 Scanning

electron micrographs of

graphite in the

metamorphic rock samples

frorn Takatsuki-yama, Japan {A

^and

B)

^and

Chungchon, Korea (Kyonggi

^massif ^schisO

(C ^and D), showing

variety of micromorphology and

the texture. A; Hexagonal _platy

graphite

crystalline material,

B;

small crystalline material

grows

^on

^the platy graphite,

C; flaky _graphite

crystalline material,

D;

closely

packed

^spheres ^of^needle

graphite.

{124)

(6)

The Association for theGeological Collaboration in Japan {AGCJ)

Observation

ef carbon

by

electron m{crotechniques

Fig. 2 Scanning electron

micrographs of

graphite in the

from Sri Lanka. A; Platy graphite

^attached ^with

granules

^on

the

surface,

B;

small spheres on

the granular

^surface,

C; booklet of hexagonal platy graphite

^crystal,

D;

rlF-etched graphite

^crystals ^containing ^clumps ^of

^closely packed

nannobacteria.

{125)

NII-Electronic

399

(7)

400 Kazuc Tazaki

ODP Izu-Bonin deep

^sea ^sediments

(Tazaki

and

Fyfe, 1992 ; Tazaki, l992) and graphite

mineral samples

from Sri Innka

^and

Korea (to be published in

separate

paper}

^were

prepared

for TE]v'I

observation

by simply letting a drop

of separate suspension

dry off

on

the

micro-

grid, The images

^obtained ^with a

JEOL

2000EX TEM

operating at

160 kV.

TEM

micrographs show a

sequence

of crys-

tallization processes

^of ^carbon ^materials

to graphite

^mineral

(Fig$. ³ ^- ^5), High-resolution

TEM

of carbon material

in

metamorphic rock showed spherical and

hemispherical

^structure

suggesting poorly

crystallized

carbon grains, 20 to 100

^nm

in diarneter (Fig. ^3). ^The

struc-

ture

should

be in

early crystallization stage

in

cornparison with

graphite showing lattice

images. Although the

carbon

phase

^structure

is too

small

to

^resotve,

there is

evidence of short-range

domain

structure showing

broad, diffuse

rings

in

electron

diffraction _patterns.

Detailed

examination of

the particles

^shows

that they

consist of an

assembly

of concentric spherical cages.

The domain having 0.3 ^- O.4

nm spacing are randomly･

distributed,

^while

other areas were almost structureless.

Another

example of

the intermediate

crys-

talline

sequence

of

carbon came

frem Izu-

Bonin deep

sea sediments

is illustrated in Fig,

4. The _particles

^of

_green

spherical materials

in the deep

sea sediments

transform into the flaky

structure of

prj.mitive graphite. 1'he

spherical and

hemispherical

structures

favor

production

^of

graphite precursors

^of ^curled-up

thin film, hexagonal, flaky (Fig. ^4A) ^and

^rib-

bon

shapes

(Fig. ^4B),

^suggesting crystal

grow- th processes from

organic carbon

to _graphite.

Electron diffraction _patterns

^of

the

curled-up

thin films

show

diffuse

rings

indicating low

crystallinity,

The flaky-shaped _graphite

as-

sociated _with small

translucent

spherules

(Fig.

4A), tends to bundle

up and

te

make ribbons which are

higher in graphite

crystallinity as

$hown

in Fig, 4B,

and

then transforms to

well- crystallized

flat

sheets of carbon

hexagons(126)

(Fig. ^5).

Hexagonal

^shape

ill TEM image

shows sharp strong spots at

0.34

nm

indicating typi-

cal well-crystallized onion-like

graphite (Fig.

5). TEM

rnicrograph

of

^nested

graphite

^shells

from Sri Lanka (Fig. ^5A)

^compare ^with ^carbon

black _graphite

standard

(Fig. 5B) both

^showing

3.4 A lattice images

clearly.

The

spherical structure appears

to

evolve

into hexagons

at

the

edge of

the growing

^amorphou$ ^structure

(Fig. ^5A, ^left

^side).

^The particles

^are ^covercd with a

thin

amorphous carbon

Iayer. The

observation of

the highly

crystallized

structure

of carbon

black

^show･s a clear

tendency to

form

separated ribbon shapes

from

onion-like

particle (Fig. ^5B).

ll-3 Auger

analysis

Auger is

unique microtechnique

ior

chemi-

cal analysis

on

the top

surface without any conductive coating material,

Auger

can

be

used

for

carbon e]ementary mapping as well as

EPMA technique. Auger

analysis was carried out with a

Perkin-Elmer I'hvsical Electronics

model

600 ^instrument

with an accelerating

voltage of 2.5 ^- 3.0 keV. Gently

crushed

bulk

samples _of

Monzosyenite, NXi'yoming (Frost

^et

aL,

1989)

w･ere mounted on

indium foil

and were

arialysed

after a

30-

sec. sputtering

to

remove atinospheric contamination oE carbon.

Auger

carbon-content map was made with an accelerating

voltage

of

3 keV

^and

beam diame- ter

of about

1"rp.

withc)ut any coating.

Sput-

ter

rates of

600 A

min-1

for Si02

^and ^a

4 kV

argon

-ion beam _were _used.

Auger

analysis

showed

carbon

distribution

on

the top

surface

of carbon

materia]s.

Grain - boundary _graphite in Monzosyenite, W'yom- ing has been _postulated

as a source of

the high

conductivit>J

in the

mantle,

but the processes

by

^which ^such

a film may form have

not

been delineated

nor

has the possibility been

^consid-

ered

that

such a

film

^may

occur in

crustal

rocks as well.

Auger-spectrometer depth

profiling (Fig. ⁶⁾

^and

scanning Auger

carbon-

(8)

The Association for theGeologicalCollaboration inJapan {AGCJ)

Observation

of carbon

by

elecLron niicrotechniques

401 Fig.3 High-

of

graphite inresolution

transmission

^electron ^micrograph

the

metamorphic rock sample

from Korea.of

spherical fingerprint like texture

(127)

(9)

The Association for theGeologicalCollaboration in Japan {AGCJ)

402 Kazue Tazaki

Fig. 4 Transmission

^electron micrographs of

flaky _graphite

with small

translucent

spherules showing

low-

crystalline

graphite (A)

^and ribbon-shaped

graphite

^with

hexagonal graphite (B)

in ODP

^sample

from Izu-Bonin 793B 27R 03, 87-89

cm.

(128)

(10)

Observation

^of ^carbon

^by

^electron microtechniques

4e3

Fig. 5 High-resolution

crystallized

graphite in

sample

(B)

^showing

^O.34

transmission

^electron ^micrograph

Sri ^Lanka (A)

^and ^carbon

^black

nm

latice images.

of well standard

(129)

(11)

404

Kazuc

Tuzaki

'

Point

1'

2 3t

100

Ca

Y

soe

Kinetic Energy

Fig. 6 Scanning Auger

spectrometer

depth _profiling

zosyenite

showing

a

high

concentration of carbon on

(Points ¹

^and

³

ârrows) ând ^no ^carbon ôn

flat

^surface

h

looe Ev

of

Wyoming Mon-

grain boundaries

(Point ^2).

content rnap

(Fig. ⁷⁾

^clearly ^showed

a high

grain - boundaries.

Points 1

and

3 in Fig, 6

correspond

to l

and

3 in Fig. 7A, indicating _presence

of

graphite

^on

grain - boundary,

whereas

point 2 has

no carbon signal,

Components

of

Fe

^and

Cr

^are

associated with carbon content.

The

carbon map shows

high

carbon

intensity

on

the grain -

boundaries

^as substantiated

by the point

^analy-

sis.

The

carbon spectrum

fr()m this

analysis

is

identical to pure

crysta]line

graphite from Sri Lanka

and

is quite clistinct from

carbonate carbon and

from

contamination carbon

from

the

vacuum system.

Sputtering

on

the

surface

indicates that the graphite films

are about

100

nm

in thick.

(1:),O) 11-4 FT-tR

Chemical binding of carbon

and

hydrogen in

carbon materlals can

be identified bv FT-IR

method.

The

^aggregaLe ^of

_graphite in

in Korea (to be

published in

^separate

_paper)

were

prepared for

FT-IR (JEOL JIR ^-5500W')

^analysis ^with ^a

beam

area

70 _ptm in diameter

and analytical

resolution of

8cm for 100 -s

_scanning

_time

using a

Ge _plate,

FT-IR

^spectra

provided information

^on

chemical compounds of

OH, CO, C02,

and

Si-

O _groups,

and evaluation of

purity ^of graphite

in

carbon materials.

FT-IR spectra of graph-

ite in

metamerphic rock show variety of car-

(12)

()bseri,ationof carbon by electron rnicretechniques

405

11･･,

Car'ts''e'n'raap

Fig. 7 Scanning ^Auger

carbon-content rnap of

W'yeming

Monzosyenite (B)

^showing

^high

^carbon

^intensity

^on

^the grain

boundaries <A)

^as substantiated

by the point

^anaiysis ^of

Fig. 6

(1131)

(13)

406 Kazue Tazaki

80

60

40

908070.60

50ge

72-g

64zF

56ti

4e:E

s

6

4

Korea _FT-IRA

1

t

'

t

'

1360

oVc1635

_,'o

340OHo

'1oooc-oB1

,,d,

,t635OH

1c:

1655ow

1t

,D

1645t655lip

lII

'

OH

E

>

,ll

h

iNs(oEo'

10DO

500

o296NCE)3000

lsoe

o296N[E}1000

500

o

294 292 ²⁹⁰

rn)

2520l5

294 292 290

c

co

2a8 2B6 2S4 2a2 2SO 27S

7em}

2S8Binding

c-

2e6

'2B4

₂₈₂ 2eO 278 Energy

leVi

c-c

rap.

lo4000

1t35mV93B58R02,94.g6cm)

56oo3200

2800 24oo 2000 t600 li2oo800

wnVENUMBERSCCM-1)

Fig.8 Fourier transform inirared spectrometer (FT-IR)

^of

graphite in the

metamorphic rock sample

from Korea

showing various

graphitization

^stages.

296 294 292

'290

3No[:8

1500

2SB

"T.UV-t

2B6 284 282 2SO 278

m)

o

296 2gq 292 290 28e 286 284 282 ?80 278

Binding Ene(gy

ieV]

Fig. 9 High--resolution C(is)

^spectra ^of

X-

ray

photoelectron

spectrochemical ana-

lyses (ESCA)

^of

green

^spherical ^clays ^show-

ing different

^carbon

binding

^ratios with

depth from 1079 to 1227

m

b.s.f. in ODP,

Izu-Bonin

samples.

bon

^compounds

in five _particles (A ^- ^E)

^sugges-

ting its

wide range of crystallinity

(Fig. ^8).

The two pitches

^around

3500

cm

-1

_and

1635

cm

-1

significantly

lost the intensity during

graphitjzation,

^which ^are

both

ascribed

to OH(132)

groups. The bands

at around

1000

cm

-1

(phenoxy group C-O)

^also

became low intense,

suggesting ^reduction of

(C-O) groups during

graphitization. The

^spectrum ^of

Si

reduced

intense

at around

800

cm

-1

_after _cornpleted

(14)

A

B

c

Observation

^ef ^carbon

^by

^electron microtechniques

407 photoelectron

spectrometer operating with an

^aperture ^of

1

mm,

analytical

^resolution ^of

1.8eV for

^all

area spectra.

Micro-ESCA technique

^revealed

presence

^of

^various ^carbon

binding in

^carbon ^materials,

High-resolution C

(is)spectra of

green spheri-

^cal ^materials

from Izu-Bonin deep sea sedi-

^ments ^showed ^various ^carbon

binding

^ratios

^with

depth from 1079 to 1227

m

b.s.f. (Fig. ^9).

The data

allow us

to determine the variance of

^carbon ^compounds ^and ^oxygen

functional groups,

^such ^as

COO, C-O, C-C

^and

graphite.

The COO binding _group

^suggest

that organic

o ^CURsoR ^cHANNEL 243

Fig. 10 Heavy-ion Rutherford

^scattering

(RILAC)

^of ^soot

(C)

^on ^metalic

^brass

^sur-

face (A) ⁱⁿ

^comparison ^with

^Si02 ^standard (B) ^showing ^the

characteristic

hydrogen,

oxygen and carbon

distributions

respective-

ly.

graphitization . The

most

crystallized graph-

ite (E) ^has

^no ^any

^OH

^stretching

^at ¹⁶³⁵

^cm

^-1, because

^of

dehydration,

^while

^less

^reactivity ^of

C-O _groups ^is ^definite. ^The ^IR

^spectra ^of

^the low

crystalline

graphite exhibit

^very

broad

and

intense OH

stretching

absorptien bands.

11-5 Micro-ESCA

ESCA is

usuful method

to know

various carbon

chemical binding

with

different

^rate.

High

resolution of

Cis

spectra of micro

ESCA

can be

separated

from different

^carbon

bind-

ing. The data

of

green

^spherical ^material

(glauconite)

^with ^organics

^from ^ODP ^Izu-

Bonin deep

sea sediments

(Tazaki

^and

^Fyfe,

1992)

were obtained with a

JEOL JSP X-ray(133)

carbon

^materials

present

ⁱⁿ

the

sample.

The C-C ^binding group is

remarkable

in

^all ^sam-

ples

^whereas

the COO ^binding group is less,

and is

absent at

1127

m

b.s.L. The COO, C-O

and

graphite

^contents ^show

the

same

tendency

as

total

carbon content, suggesting

the trans- forrnation processes

^of

green

^spherical

inte-

rior.

The

carbon

binding

^ratio ^reflects

^the degree

^of

polyrnerization by esterification

with organie materials.

The green

^spherical

materials at

1135

m

b.s.f.

show

a trend involv-

ing less

of

hydrogen

^and ^oxygen.

The ^final

stable

product

^of

the C

cis)material seems

to be

graphite, The

result suggests

that COO, ^C-O

and

C-C

ratios

in the green ^spherical

^materials

decrease

^with

graphitization during diagene-

sis.

11-6 RILAC

RILAC

^method

can be

used

for

evaluation of atomospheric

contaminated

^carbon

from the

structural c.arbon,

Hydrogen,

oxygen and carbon

distribution in the

soot sample were examined

by heavy-ion ^Rutherford

^scattering

using

the RIKEN ^heayy-ion linear

acceTerator

-

(RILAC). ^The

^soot ^sample ^was ^coilected

^from

city-propan gass burning

^at

fi･re,

^and

precipitated

^on

the

metalic

brass plate. A 51.2

MeV Ar6'

^or

Cu2' beam

^of

50

^nA ^were

used

^as

incident particles, The beam size

^was ^about

1.5

mm ×

3

mm on a

target

angled at,20

',

detecter

^angled ^at

³⁰

Ô, ând ân âluminium

^foil

NII-Electronic

(15)

408 Kazue Tazaki

12 _"m in thick (Minami

^et ^al,,

^1989, ^1990).

RILAC depth profiles indicate II, O

and

C

contents of metale

brass plate (Fig. IeA), Si02

standard sample

(Fig. ^10B)

^and ^soot ^on

^the

metalic

surface of A (Fig. ^10C). ^The

^soot

sample was collected

from propane gas burnt

precipitate on the

^metallic

brass plate. The profiles

^clearly ^show significant

differences

among

three

samples.

The

^metallic

_plate (A)

compose of surface water, surface oxygen and surface carbon, whereas

the Si02

^standard

sample

(B)

^shows ^relatively

^high

^absorbed

water,

higher

^oxygen

in

crystalline structure and

quite low

surface carbon,

The

crystalline carbon

is

^not

found in the profile B. The

^soot

sample

(C) ⁱⁿ

^comparison ^with ^sample

^A

^and

B,

^clearly ^shows

both

^surface ^and ^absorbed

water contents,

low

surface oxygen and

quite high both

^surface ^and crystalline carbon.

Note

that the

characteristic

hilly _peak

of structural carbon

is

^visible

in the

soot

profile (Fig, 10C), The hemispherical

carbon slope of

depth pro- file shows that carbon atoms are distributed

uniformly

in the

soot structure.

The

absorbed

water

on the surface of soot shows

sharp

peak

compared with

its

metal and

Si02

standard samples.

The Si02

standard

profile

^showing

high _platform indicates that high

^structural

oxygen

is in

uniform

distribution.

III Discussions Carbon changes to graphite

In this

study carbon materials showing variety of

forms

^and ^wide ^range ^of micro-struc-

ture

were evaluated

bv

electron microtechni-

ques, Carbon

^supplies

from the transport

SYstem of

C02 ^- 02 ^- H20 in the Earth. The

transformation processes

^of ^carbon ^material

to graphite is

summarized as

follows: The biosphere-living

^matter

dominated by C-H-O-

N

^-

_adsorption

of

H20

on

the

surface -

composition of COOH'in the

structure -

dehydration'

of carbon･ material'under reduction

condition ---)

_carbon

precipita-

tion

^- carbon crystallization -

(134)

graphite

^mineral

fermation. For

^carbon ^mon-

oxide,

there

are many

individual

sources

in the

Earth. The distribution

^of atmospheric

CO is

not comparable

to that for CH4

or

C02. Mas-

sive

transport

of

inorganic

^carbon ^components

occurs

through the biosphere

which

is

assQciat-

ed with various

types

of

biomineralization

processes (Gammon

^and

^Charlson, ^1993), ^The biological _processes

^occur ^at

the

microlevel and

influence the

macro systems.

In the

car-

bon transformation processes the

nannobacter-

ia trigger

or catalyze

initial precipitation in

a very complex microbial world where submi- cron-scale ehemical reactions

is supplied

<Krumbein

^and

Werner, 1983 ; Folk, 1993).

Carbon

materials

formed by both inorganic

and

biological _processes

^must

have the

^most

sensitive response

to global

^change ^of

C02.

Carbon ⁱⁿ

^rock

samples

In this

study

Ayger-spectrometer depth

profiling

^and ^carbon ^content ^map

(Fig. ⁶

^and

⁷⁾

showed a

high

grain boundaries

of

the Sybille Monzosyenite

having high

^electrical conductivity.

The film

of

graphite

^may

be ^formed

on

grain- boundaries during

cooling, even

if _graphite is

not

stabie in the high-grade

mineral assem-

blage in the presence ^oi CO, ^-

^rich

^fluids, such as

^many

igneous

rocks and

granulites (Frost

^et

al.,

1989). FT-IR

spectra of

Korean _graphite

showing

different 0H

and

C-O

absorbed

bands

are related with

the degree

^of crystalinity

(Fig,

8). High

resolution

of C(is) spectra

of micro

ESCA

of rocks and sediments

can discriminate

various carbon

chemical binding,

such as

COO, C-O, C-C,

and

graphite (Fig. ^9). Hydrothermal iluxes

ef carbon

into

surface aquatic systerns will

be

significant role

for

carbon

-

_cycle,

but the globai flux from these processes ^are

^not

well

quantified.

Carbon in

soot

RILAC

^spectra ^of ^soot ^showed characteris-

tic structural

carbon, oxygen and

hydrogen

(16)

Observation

of carbon

by

electron micrutechniques

ions

comparing with standards metallic

plate

and

SiO, (Fig. 10). A

^nucleation ^of

the gaseous

could occur when soot

is _produced by the pyrolysis

^of

hydrocarbons

at

lo", temperature.

IIewever, in

a

flame, there is

no

true

nuclea-

tion (Lahaye, ^1992). ^The

^surface

^growth

^of

^the

aggregates

is

responsible

for the

stability of soot aggregates,

High-resolution ^TEM

^mi-

cromorphology

^of oil-clerived soot

(Tazaki

and Watanabe, ¹⁹⁹²⁾

^support

^this ^RILAC ^data.

The fine

^soot

particle have

no

true

nucleation,

but finger-printed

microstructure of

poorly graphitized ^carbon ^spherules is

recognized.

They

are stabilized

by

a continueus carbon network, as shown

in RILAC

results

(Fig. ^10).

The

spectra can

be

used

for _evaluation

of atmospheric contamination carbon

from

^struc-

tural

carbon.

Crystallization

^of ^organic ^carbon

During the graphitization,

^amorphous ^car-

bon transforms itself into high

crystalline

graphite (Hishiyama

^et ^al,,

^1992). ^In ^this

study, the electren

^microscopy ^reveals

the crystal growth processes

^of ^carbon ^materials.

Precursor

carbon ^materials show

spherules, tubular, flakes, thin films, flat

sheets, and ribbon

forms. In

all

these

stages

the

nannobacteria

trigger initial precipitation, ^then

dissolved

calcium carbenate "iill

precipitate

abiotically upon

the bacterially precipitated seed

^crystals

(Folk, ^1993),

On the

other

hand, the fixed

carbon may･

achieved

through the

agency of

thermal treat-

ment alone.

Well - known

examples are

the

nongraphitizing carbons and carbon

blacks.

Organisms

can

live in liquids

up

to tempera-

tures

^avobe

100

^'C.

There is increasing

^evi-

dence that

erganisms are

present in deep

ground

^water ^and

hot black

^smorker

in deep

sea sediments,

but little is _yet know

abeut

such

high temperature

systems.

IV Conclusions

Carbon

and

graphite

^are ^very

important(135)

,109

materials which exhibit unique

ability to form

a wide range of structures

in the Earth, We have to

ebserve

the

crystallographic structure

on

the _ptm

and nm scale

in

^order

to better

under$tand

the properties

^of ^carbon ^and

graph-

ite. V'arious

microtechniques

for

^study ^of

carbon

in the Earth

were

introduced in this paper. The

electron microscopy revealed

the texture,

micromorphology,

growing processes,

origin, crystalinity and

the distribution

^of ^car-

bon. Amorphous

carbon

transforms itself into high

crystalline

graphite. Precursor

^carbon

materials exhibit various morphology as

spherures,

tubular, flakes, thin films, flat

sheets, and ribbon

textures. Bacteria _probably

p]ay

^a

prominant

^role

in

catalyzing

the precipi- tation

of carbon materials,

Hexagonal

onion-

11ke texture is the

^mest

$table form

^of ^carbon.

Auger-spectrometer depth profiling

^and

the

content ^map showed a

high

grain boundaries

of

the

minerals

in

the Sybille Monzosyenite having high

^electri-

cal conductivity.

FT'IR

spectra of

graphite

reflects

the degree

^of crystalinity showing

different {ntensity

of

OH

and

C-C

absorbed

bands. High

^resolution ^of

Cas)

^spectra

of

micro

ESCA

can

discriminate different

carbon chemieal

bindings

of

COO, C-O, C-C, ancl graphite. RILAC

spectra of soot show･ed characteristic recoiled carbon which can

be

^used

for

evaluatien of atmosferic contamination carbon

from

^structural

carbon. Carbon partic-

ulates are significant

in the global flux having

the

^most sensitive response

to global

^change.

Acknowledgments

We thank Dr. M. Aratani in The lnstitute

^of

Phvsical and Chemical ^Research,

^and

^the

^staff

in JEOL ^Ltd. ^for ^their ^technical

assistances.

This

work was supported

by _grants from the

National Science ^Research Fund

administered

by the Monbusho (Japanese ^Ministry

^of

^Educa-

tion, Science

^and

Culture).

(17)

41U

Kazue

1'azaki

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