W. Richard Bowen and Nidal Hilal 4

72 2. MEASUREMENT OF PARTICLE ANd SURFACE INTERACTIONS
n o Ion number concentration in bulk m �3
n oi
Refractive index of component i �
p Pressure N m �2
Q Charge on plates C
r Interparticle separation (centre to centre) m
r s Radius of the spherical particle m
R Gas constant J mol �1 K �1
R i Radius of sphere i m
R p Radius of the probe sphere m
R t Radius of curvature of the probe tip m
S � Surface area of spherical shell m
T Absolute temperature K
u i Dipole moment of molecule or atom i C m
v Velocity of the probe m s �1
v f Poisson ratios for a flat surface �
v i Orbiting frequency of electron i s �1
v s Poisson ratio for a sphere �
V Volume of container m 3
V A Attractive interaction energy J
V R Repulsive interaction energy J
V T Total interaction energy J
�V Voltage difference V
w (r) Interaction potential J
W(D) Interaction energy per unit area as a function of
distance
J m�2 Wa Work of adhesion between two bodies J
xjtc Cantilever deflection due to the jump-in m
X ˆ
COO Fraction of carboxyl groups ionised �
zi Valence �
z0 Effective range of the surface forces m
Z� Charge number due to negative groups on the
BSA surface
�
Z� Charge number due to positive groups on the
BSA surface
�
ZAB Charge number from acid–base equilibria �