absolute activity

?

e ^?? where ?=1/ k _B T and ? is the chemical potential.

absorptivity

? _r

The fraction of incident radiation that is absorbed by a surface.

acceptor

An impurity in a semiconductor that takes an electron from the valence band, creating a hole.

activity

?

In this book, short for absolute activity (q.v.). ^[1]

adiabatic process

A process in which the occupancies of quantum states do not change.

adiabatic

Adiathermal.

adiathermal

Permitting no heat flow; thermally isolating or isolated.

analytic function

A function all of whose derivatives exist.

angular frequency

?

2 ??. Rate of oscillation in radians per second.

anisotropic

With properties that depend on direction.

atomic mass unit

amu

Unit of mass in which the proton mass M _H=1.

Avogadro s kmolar number

N _A

Number of particles in one kmole of a substance. ^[2]

Avogadro s number

Number of particles in one mole of a substance.

band

A continuum of allowed electron states in a solid.

band edge

The lowest point in the conduction band or the highest in the valence band.

bandgap

Energy gap (q.v.).

barrier height

Potential barrier opposing diffusion of carriers across p-n junction.

binomial expansion

The series (1+ x) ^a=1+ ax+ a( a ?1) x ²