Pierson Hugh O. Handbook of carbon, graphite, diamond and fullerene. New Jersey / carbon

Glossary

377

Dubinin

Equation:

The

expression

of

Dubinin’s

theory

for the

filling

of

micropores

(see

Ch. 10, Ref.

16).

Electromagnetic

interference

(EMI):

A generally

undesirable

“noise” in

the

form

of

magnetic

or

electrical

energy,

mostly

occurring

the

radio-

frequency

portion

of the

electromagnetic

spectrum

(1 kHz to 10 GHz).

Sources

of

EMI

are

lightning,

computers, communication

systems,

and

many others.

Electron

Volt

(ev):

The

unit

of energy

accumulated

by a particle

with

one

unit

of electrical

charge

while

passing

through

a potential

difference

of one

volt.

It is used

to

measure

the

energy

of particles

but

is not

a SI

unit.

1eV

= 1.602

x 1O-l9 Joule.

Epitaxy:

The

growth

on

a crystalline

substrate of a crystalline

substance

that

has

essentially

the

same

crystal

parameters

as

the

substrate.

The

substance

can

be grown

from

a gas

(gas-phase

epitaxy)

or from

a liquid

(liquid-phase epitaxy).

Galvanic

Corrosion:

Accelerated

corrosion

of a metal due to an electrical

contact

with

a more

noble metal or non-metallic

conductor.

Galvanic

Couple: A

pair

of

dissimilar

conductors,

commonly

metal,

in

electrical

contact.

Gas-Phase

Epitaxy:

See

Epitaxy.

Ground

State:

The

state

of an

atom

at its

minimum

energy

level.

The

electrons

are as close

to the

nucleus

as they

can

be.

In the

ground

state,

the atom cannot

radiate

energy.

A number

of possible orbits

extend

outward

from

the

nucleus

where

electrons

can

be lifted to form the

excited

states.

Any

electron

can

be

lifted

from

the

ground

state

to

the

excited

state

by

absorbing

a definite

amount

of energy.

igneous

Rock:

A

rock

formed

by

solidification

from

the

molten

state

(molten

magma).

index of Refraction:

The

ratio

of the

velocity

of light

in

air to the

velocity

of light

in a substance

at a given

wavelength.

378

Carbon,

Graphite,

Diamond,

and

Fullerenes

Indirect-Bandgap

Semiconductor:

A semiconductor

material

such

as

silicon

in which

avalence

electron

with

energy E, cannot

be excited directly

across

the forbidden

band

between

the valence

and

conduction

bands (the

energy

gap being

Es), but requires

a change in momentum.

Conversely,

in

a direct-bandgap

semiconductor

such

as gallium arsenide,

the electron

can

make

the

transition

directly.

It does

so

by absorbing

or emitting

a photon

of energy

E,.

Ionic

Bond:

Atomic

bonding

due

to

electrostatic

attraction

between

charged

particles

(ions)

resulting

from the

transfer

of electrons.

Ionization

Potential:

The

minimum

energy

necessary

to

remove

an

electron

from an atom or molecule

to such

a distance

that

no electrostatic

interaction

remains

between

the

electron

and the ion.

Synonym:

ionization

energy.

Units:

electron

volt

or Joule

per mole.

Isomers:

Molecules

with the same

number

of atoms

of the same

elements

but with

different

structural

arrangements

and

properties.

lsomerization

is

the

process

that

causes

a substance

to be changed

into

an isomer.

Isotope:

One of two or more atoms

of the same element

with

the

same

number

of protons

in the

nucleus

but

different

number

of neutrons.

Kimberlite:

An

igneous

rock (peridotire)

containing

garnet

and

olivine

which

probably

originated

in the

upper mantle

and

was

forced

upwards

in

volcanic

pipes.

Lonsdaleite:

A naturally

occurring

hexagonal

form

of diamond

sometimes

found

in

meteorites.

Metallic

Bond:

The interatomic

chemical

bond

in metals characterized

by

delocalized

electrons in the energy bands.

The

atoms are considered

to be

ionized with

the

positive ions occupying

the lattice

positions. The valence

electrons

are free

to move. The

bonding

force is the

electrostatic attraction

between

ions and

electrons.

Glossary

379

Metamorphic Rock:

A rock

that

has

been submitted

to changes

in

mineralogy and texture

by pressure

and temperature in the

earth’s interior.

Molar Density: Total

number

of atoms

per cm3 divided

by Avogadro’s

number.

Molecule: A group

of atoms

held together

by covalent

or coordinate

bonds

(found

in most

covalent

compounds).

Ionic compounds

do not have

single

molecule

since

they

are

a

collection

of

ions

with

opposite

charges.

A

diatomic

molecule

is formed

by two atoms

(e.g.,

H,,

HCI) and

a polyatomic

molecule

by several

atoms

(e.g., carbon

C,,

C,,

etc.)

Node:

A point

or region

in a standing

wave in which

a given

characteristic

of the

wave

motion,

such

as particle

velocity

or displacement,

or pressure

amplitude,

has

a minimum or zero value.

Orbital: A region in which

an electron

may be found

in an atom or molecule

(see Standing Wave),

Pack Cementation:

A coating

process

relying

on

chemical

transport

in a

closed

system.

Paull’s Exclusion

Principle:

The principle

that

no two identical

elemen-

tary particles

having

half-integer

spin

(fermion)

in any system

can

be in the

same

quantum

state

(i.e.,

have the same

set of quantum

numbers).

In order

to account

for the various

spectral characteristics

of the

different elements,

one must

assume

that

no two electrons

in a given

atom can

have

all four

quantum

numbers

identical.

This

means

that,

in

any

orbit

(circular,

elliptical,

or tilted),

two electrons

at most

may

be present; and

of these

two,

one must

spin clockwise

and the other must

spin

counterclockwise.

Thus,

the presence

of two

electrons

of opposite

spin

in a given

orbit

excludes

other

electrons.

Peridotite: A coarse-grained

mafic igneous

rock composed

of olivine

with

accessory

amounts

of pyroxene

and

amphibole

but little or no feldspar.

Quantum

Numbers:

The

numbers

characterizing a region in which an

electron may move. These

numbers are “n”,the principal quantum number

(ground state is n = 1, exited states

have n = 2, 3 or more), “I”,the orbital

quantum

number,

“m”, the magnetic

quantum number,

and “s”, the spin

quantum

number

(l/2

and -l/2) (see

Pauli’s Exclusion

Principle).

Radiation

Energy:

The energy of the quantum of radiation hv, being equal

to the energy

difference of the states, No electron radiates energy as long

as it remains

in one of the orbital energy states; energy occurs only when

an electron goes form a higher energy state to a lower one.

Resilience:

The amount of potential energy stored in an elastic substance

by means

of elastic deformation. It is usually defined as the work required

to deform

an elastic

body to the elastic limit divided by the volume of the

body.

Glossary

381

Sigma (a) Bond:

The

bond

resulting

from

the

sigma

orbital,

this

orbital

being a molecular

orbital

produced

by overlap

along the line

of axes,

such

as in a carbon

molecule.

Spin: The

intrisic

angular

momentum

of an elementary

particle

or group

of

particles.

Spin is characterized

by the quantum

number

I‘s”. Because

of

their spin,

particles

also have their own intrinsic

magnetic

moments.

Standing Wave (or Stationary Wave): A wave

incident

on the

boundary

of the transmitting

medium, reflected

either wholly

or partially

according

to

the boundary

conditions.

The reflected

wave

is superimposed

on

the

incident

wave

resulting

in an interference

pattern

of nodes

and

antinodes.

The motion

of the

electron

can

be considered

as a standing

wave

and

can

be expressed

by a differential

equation

(for the

hydrogen

atom

only).

The

solutions

(wave functions)

determine

the

coordinates

of the electron,

the

nucleus

being

the

origin

of the

coordinate

system.

The

wave

functions

are

Stereospecific:

Describing

chemical

reactions

that

give products with

a

particular

arrangement

of atoms

in space.

Sub-Shell: A division

of an

electron

shell.

The

electron

shell of principal

quantum

number

n can be

divided

into

n sub-shells.

The

first

has

two

electrons

and

subsequent

ones

can

contain

four

more than

the preceding

one (6,10,14,18,

etc.).

The

sub-shells

are symbolized

ass,

p, d, f, g, hand

i (these letters

being derived

from

atomic

spectroscopy

nomenclature).

The

first electron

shell

has

only

the

is

sub-shell, the second

contains

a

2s

subsheli

and

a 2p subshell,

etc.

Temperature

Coefficient

of Resistance:

The

change

(usually

small)

in

the resistance

of a material

as a function

of the

changes

of its thermody-

iii - V, ii - Vi Semiconductors:

Compounds

with

semiconducting proper-

ties consisting

of elements

of Groups

III and V such

as gallium

arsenide

or

elements

of Groups

II and

VI such

as zinc

selenide.

Tow:

A loose,

essentially

untwisted

strand

of synthetic

fibers.

Uitramafic Rock: An igneous rock

consisting

dominantly

of mafic

miner-

als,

containing

less

than

10%

feldspar

and

including dunite,

peridorite,

amphibolite,

and

pyroxenite.

Valence Electron: An electron

located

in the

outer

shell

of an atom

which

is able to

participate

in the

formation

of chemical

bonds.

Van der Waais’ Forces: Interatomic

and

intermolecular

forces

of electro-

static

origin.

These

forces

arise due to

the

small

instantaneous

dipole

moments

of the

atoms. They are much

weaker

than valence-bond

forces

and inversely

proportional

to the seventh

power

of the distance

between

the

particles

(atoms

or molecules).

Vapor: A gas at a temperature below

the

critical

temperature

so that

it can

be liquefied by compression

without

lowering

the

temperature.

Wave Function: A mathematical

expression

representing

the coordinates

of a

particle

(i.e.,

an

electron)

in space.

It appears

in the

Schroedinger

equation

in wave

mechanics.

Glossary

383

REFERENCES

Dictionary

of Chemistry, (J. Daintith,

ed.), Oxford University Press, Oxford,

UK (1992)

Dictionary

of Physics,

(v.

Illingworth, ed.),

Penguin

Books,

London,

UK

(1991)

Cram,

D. J. and Hammond,

G. S.,

Organic

Chemistry,

McGraw-Hill,

New

York

(1964)

Eggers, D. F., Jr., et al., PhysicalChemistry,

John Wiley&Sons,

New York

(1964)

Press,

F. and Siever,

R., The Earth,

W. H. Freeman & Co., San Francisco,

CA (1974)