Vibrational spectroscopy of aqueous solutions at high concentrations: Raman and inelastic neutron scattering

239

Journal of Molecule Stnrcture. 113 (19s) 239-260 Elsevler Science Publishers B V , Amsterdam - Pnnted m The Netherlands

VIBRATIO!AL AlitI

SPECTROSCOPY OF AQUEOUS SOLUTIOX

INELASTIC

AT HIGH

CONCENTRATIOX,:

RA’IAN

F(EUTRON SCATTERIRG

M. P . FONTANA Dlpartlmento

dl

G :MISANO,

Fislca

and

P.MIGLIARDO,

Istltuto

dl

Flslca

GNSY,

University

of

Par-ma,

Italy

F.YARDERLINGH

and

GNS’I,

Unlverslty

of

Yesslna,

Italy

ABSTRACT We review work performed by our group on vibrational spectroscopy of water and aqueous solutions or strong II-I electrolytes at high concentrations Evidence shall be oresented for the existence of intermediate range, soluteconnected, orderea nuous vIbrationa Raman and as ZnClZ, trasonic

patches density

inelastic

vlbratlonal nodes yield amorphous solids. We shall

, whose collective of stares, as in

neutron

scattering

NlClp, C&r2, CdC12. attenuation rrlll also

results,

obtained

such

Other results, be dlscussed.

for

a contlreview

electrolytes

as EXAFS,

viscosity

such and

ul-

I :lTRODUCTI OR Vibrational sively lytes ted

spectroscopy,

used at

to

study

high

due

to

in

features

on

simple

solute might

from

(we

shall

anions,

such

as

frequency

these in

that

in

cases the

0022-2860/82/$03

not f-1

Clost

the

(say

=or

wz 400

cm -‘).

those

of

water

In

the

nitrates

or

present

which

the

water

and

have

been

spectra

continuum

00

part

0 1981

of

low

In

the

Elsener

work

case

the

spectra

spectra

analyzed

of

ln

with

was disregarded

Science PubIshers

show specific

oeaks

region, spectra

which

B V

are

such

hardly

complex

ions

are

complex

solute-connected

with are

where

with

metals)

contributions

solute-lnduwater.

electrolytes

together

eytenelectro -

solvent,

spectral

alkali

mainly

the

been

strong

on the

do not

simple of

solute

spectra

regions

th e solution

of

of

focussed

frequency

has

solutions

electrolytes

sulfates

are

the

the

ln

scattering,

aqueous

spectral

and

peaks

the

of

solutions

consider

Raman of

characteristic

eiectrolyte

arise

present

continuum,

the

particularly

structure (1).

vibrations,

dlstlngulsnable

low

and ionic

concentraticns

modlflcatlons

In fact

the

an not

unstructured separable.

an analytical or

subtracted

In

approach, away,

and

after

the peaxs,

to one lower

or another

comoarable to form

with

trolytes

ionic

lons.

in fact

such

that

as NiC72,

range

above

termedlate

range

ordered

of

of

the

the

wn1ch

solute.

type

ln such

over

sities

similar

1n the

low

whose to

that

without

the

Crete

In this

serse

be similar tions

to that

we are

dealing

CuBr2,

with

1s best

the

solvated

cations

strength

distances.

long

spectra7

The the

1n turn

7eads

Thus

the

region

arbitrary

solids,

soectroscopy

of

the

of collective

vi-

of

density

spectral and

den-

analyzed

continuum these

highly

1n this

be considered,

structure ions

or neutron

into

anions

the

be considered

separation

of which

time

in-

struc-

complex

to a vibrational

Raman

should

con-

of an

a local

existence

elec-

II-I

crystal

the

residence

tend

results

1n terms

and

do

a typical

the

to form

to allow

the v1bratlonal

m:ght

described

for

becones

which

exist

to reproduce

sufficient

distance

of strong

there

at

minded

of experimental

solutions ZnBrp,

assigned

be Justified

ions

terds

of a solid

of amorohous

metal

a rumber

were

simple

1nterionic

which

words,

somewhat

it may

those

of aqueous

dispersion

frequency

while

be excessively

for

solution

with

subcomnonents.

average

quite

1nter7on1c

as continua, parts.

the

structure

1s sufficiently

excitations

of states,

CdC72,

several

structure

brat1ona7

ZnClp,

interact

the

years case

which

may

especially

in the

In other

MeXg-"

extends

when

size,

into

approach,

c,
In recent

centration

ture

Such

for

to saturation,

the

complex

shown

(say,

up

deconvolut1on

species.

ionic

concentrations

concentrations

have

eventual

and

systens

dlswould

concentrated

context,

solu-

a particular

class. In tnis witn

Paper

particular

inelastic

the

Ray Absorption Scattering),

review on

Fine

Wnenever

obtained

and

S4NS

ultrasonic

and

techniques

and

which

led

to these

investigations,

useful

by other

Structure),

vlscoslty

the work

the spectroscopic

scattering.

rosultc

of

scme

SAXS

relevant, such

(Small

namely he

shall

as EYAFS

Angle

results, Raman

and

21s~

brief-

(Extended

Neutron

and

X-

X-ray

attenuation.

SDECTPOSCOPY

The nal

shall

emphasis

neutron

7y discuss

lU!+h

we

Ranan

cross

to the Fourier

d1electnc

section

susceptlb171ty

in which

furthermore

comoared

to

for

transform

any of

vibrational

of

interacting

space-time

fluctuations.

eqJ111brium

the average

system

the

atomic

In a non-magnetic positions

period,

the

particles

autocorrelation

may

electronic

be defined

scattered

1s proportio-

function

for

intensity

of

the

insulator, times ~117

long

be con-

241 netted

with

ling

the

function

FR(w)

which

rizabillty

is

ge

coherence,

spaclal

event

- %

ki

where the K

will

4

=

modulated

to unit

In

ded

couple

density of

tes

(2).

g(w) of

zed

Raman

will

yield

then

the

the

the

atomic

or

the

system

possesses

condition

(1)

the

oolarizabillty

pOla-

nolecular

for

such

of

as

vi11

long

the

ran-

scattering

be

this

changes

FR(w)

Gose-Einstein the

two may

w/n(w,T)+l

is

the

or g(w),

mode; Raman

functions be written

since

k4

modes

rule were

In

to

the to

and

loss

conserved.

of

systems

snacial

scatEerin2 The

Raman

proportional

true of

to

vibrational

density

particles

with

associated

fluid,

whereas

the

ln-

and

disordered

the

will

the

isolated

coprovisoec-

the

con-

of

stg

internal the

de-

depolari-

oolarlzed

spectrum

(3) coupling may

function

not

always

becones

FR(w)

ard

be a valid

a simple

product,

g(w) one

-

and

the

as-

(2)

g(w)

population

physically

= F,(w)

due

sysrem

with

relevant

ty-

= I(w)

and

assumption

the

they

present.

aoply

solid

the

if

distribution

particle

between

a selectlon

as

energy

a disordered

intensity

+ 1)/w)

the

FR(,+)

connected

as

of

Now, only

may contribute

spect-al

simplifying

scattered

to

and

single

between

act

light

were

modes

k = wavevector

destroyed(-)

respond

cease

a molecular

coupling

and

is

will

and

visible

will

will

function

case

or

frequencies

vibrational

vectors

wave

for

(1)

crystal

all

convolution

n(w,T)

Thus

solids

the

dynamic

tmperature

IR(w)

like

created(+)

vibrational

molecular

IR tw) = E(n(w,T)

Sl

a Bragg-

constant,

the

coupling

In

the

depolarized

where

If

light

oe a continuous

spectrum

neglected-

of

to

freedom,

the

scattered

lattice

q

the

will

volutlon

is

motion.

Is,

(phonon)

cells

therefore

If

crysta

scattering.

amorphous

they

and

a

the

herence,

grees

atonic

strongly

(1)

where

dispersion

tral

in

excitation

teractlng

as

as

the

how

=+k

CC 27/a,

such

by

= incident

1,s collective

contribute

no

describes

COUP-

hold:

k

1 ¶S

correlation function through a

displacement-displacement

g(H)

factor. quantity

Thus is

the

to

study reduced

spectral Ranan

and intec

242 III the

case

of a dlscrete

IR(w)

becomes

irrelevant;

IR(w)

is much

more

sharp for

line

spectrum

a continuum

the

difference

spectral

density

quency

spectrum

CdCl

1

I

I

of

9

150 350 R4M4N SHIFT km-‘)

1. Experimental

L50

Rarcan spectra

for

ref.

is broad,

frequency

dent

with

NlC12

and

tions.

(4)).

a single nuun

vibrational

ZnC12

solutions.

saturated The

broaden Zn-Cl by

the

course

of states.

In fig.

2 we

solution

polarized

peaks

density

due

of ZnCl

soectra

show

‘co the Zn-Cl

into bonds

were

part

Raman

spectra

absent

(fig.

2' strong,

bonds.

a continuum

obtained

the

us

The

kind

consider

polarized

in fig.

soectral

of some

4).

show and

Let

3 the

relatively

of

local

for molten

ZnCIZ

colnclpeak

to the

in

the solu-

however

cne,

but

a conti-

scectra

that

result where

pre-

1s not

the case

particle

(5),

with

contrlbutlon

of for

a

spectra. molecular

these

be expected This

and

due

reduced

shows

a

crystalline

bond

depolarized

as would

or glassy

the

instance

single

"retwork".

NlClZ

lndeoendent

Such

corresponding

spectrum

dlstrlbution,

hand,

vibrational

spectrlum

for

sharp,

depolarized

of

particle

and

of pu-

feature

1s clearly

The

of

and

oractically

of He-Hal

a spec-

to that

fairly

CdC12.

therefore sence

has

does

contribution,

the main

spectra

such which

concentration,

oeak

in the

the saturated solutions of (b) CdClZ, (d) SrClp and for (e) pure water. Exci Catlon power: 100 mW, ccunting time/ channel 0.6 set; scan speed 700 (n-l/ sec.(The top spectrum 1s from a single crystal of CdClZ 2.5 HZ0 (a) (From

is

the other

additional

solute

solution

ions,

solutions

2

The

electrolytes On

and

(4).

that

IS similar

I-I

hhlch

ilg.

of

fre-

of water

electrolyte,

which

strong

low

solutions

complex

re water.

I

the

the SrC12

II-I

simole

and

show

spectra

of

form

trum

150

and

the use

to daonstrate

stronq not

1 we

saturated

shown

I

however,

Raman

some

,

I(w)

appropriate. In fig.

50

between

ueaks

if the is confirmed water

1s of

343 The

value

dependence

(b)

zation

Zn CL2 In

.r

try

,

---‘~___,

25 STOKES

0

I

75

SHIFT,meV

main

(I

t1%

2. Polarized )

(Ivv)

and

ghly

depolarized

Raman spectra or a saturated of ZnCl lrl D 0 2 2

for

the

coordinated form for

the

ionic

ZnC12

IilCl,, and

and

which

complexes,

would

square

most

planar

for

the complex the main

soectrunr. and

likely

be octahedral

CuCl,.

Such

in hl This

low

values

of halide

the metal or

so

to to-

complexes.

conclusions

The

polarizec,

10 exclude

by

fc:-

NlC12

vlbrarlons

number

give

sve-

be assigned

symmetric

n,

can

of

strongly

may

tena

depolari -

local

with

syrrmetrlc

would

sol%

the

In ZnCl*

are

thus

tally Fig.

on

ln the Raman

lutlons and

Raman

structure

peaks

frequency

= I /I

connected

turss

the

the

ratio

and

Ions

1

of

lnformatlon

‘I””

:

and

ions

ion

to

tetrahedral are

In agree

1

1 \ 50

-.

_ 1Z.O

0

AE,meV Fig.

3. Reouced

butions 029;

from

depolat-lzed

neutron

(e) saturated

Raman

scarrering solution

intensity (01

of

ZnC12

for in

(x) aid

(a).DpO, H20.

50

generalized

(b,c,d):so;utlons

‘C

frequency of

disiri

ZnC12

In -

lment which

previous the

thermore,

the

complex the tlon

ln fig

local ions

solvent

may Fig.

4. Reduced

tensity

depolarized

of molten

ZnClZ.

Raman (From.

in

of about

5). X-Ray flc

absorption

atom

direct

The

above

fitting

infcrmatlon

mediately

of LURE,

tion

as a source

CuBrZ, tod

ZnBr,,

(8).

with

lutlons,

was

on

Orsay, was

about At

found,

Br 80;

atomic

the

ZM,

absorbing and

of

the

PULS,

Zn atoms

10~

concentt-atlons

the

EYAFS

oscillation

for

and

EXAFS

of

f-1

the

the

EXAFS

where both

being

complexed solutes

due

of the

For

into

atom

of

man

shifts,

respectively

(From

ref.6):

the

the

radla-

investlgawere

saturated

so-

of complexes oxygen

solvated

saturation were

structure

a distance

from

least

of Zn Ions

tratlons

was

further

EXAFS

Hell

of

the of

the

fitted local

the

solutes,

absorbing

6 w. The

caoaclty

backcations

the

very

the oarameters

of at

the facill-

Cu atoms

ZnBrZ

to

crystalline for

be

no evidence

At

im-

-2 ZnBr tetrahedral 4

oscillations with

the atoms

in particular

50%

predominantly

(flg.6).

gives

synchrotron

could

scattering

Frg. 5. Concentratlan dependence of de polarization ratio for CdCl? and &Cl 2 solutions at 230 and 285' cm-' Ra

of

halogen

(O.bM)

ef

of a speci-

(using

with

complexes.

spec

Absorptlon

oscillations

soectroscopy

and

inferences

the continuum

K edge

distribution

approximately CuBri*

modulates

Italy)

the

is a diffractive

the electrolytes,

of metal

solutions, planar

of

Frascati,

some

K edges

square

edge,

numoer atom.

to study

ooth

which

ccmoonents

the

saturated into

Fourier

separation,

France

feet

sol:

by EXAFS

X-Ray

of

concentra the

These

directly

Extended

Structure

that

to dominate

(6).

be tested

the

by

whereupon

begins

Fine

ionization

the

used

for which

In CuBrZ

complexed

groups.

of

surrounding

ties

the

about

to a typical

ordering

troscopy.

ref.

5. indicates

symmetry

up

Fur

denenden -

is dominated

te structure local

(1).

concentration

ce of Q shown that

studies

completing

at high

concen-

confirmed

by

243

A

“e

EXAFS

measurements

which

the

ding

either

or

Raman

tion

however

n .fi,-

stence

:

due

IL: ma

Energylrrl

700

which that Fig

6

EXAFS

results

two

the of

local

the

of

the

of

solute

together

for

the of

such

ordered

ordering

EYAFS

ordered

density

intermediate

by ad-

Neither

evidence

interactlon

in

the determlna-

techniques

of a vibratIona

to form

a

size

conclusive

to the

(9).

allows

the

solutions

.ras varied

IiBr or SrCl?

tne average

do yield

.

ion content

scattering

of

patch,

01

Br

in mixed

exl-

states

comole,xes

patches

ln

is very

close

in crystalline

form

to

onaqueous

solutions of ZnBr2 at the i!n kedge. Too solid ZnGrp, middlealmost saturated solution (8 03 II), bottom. dilute solution (1 29 M) (From ref 3)

I4EUTRON The

SCATTERING existence

probed

of

directly

trast

between

(10).

Considering

neity

of

small

and

factor SAS

the

small

using

analysis

the data

slgnal

of was

so small

contribution

lndlcate

;ome

it was

on the

(11)

showed

planned

performed

its

synchrotron

that

which

and

were

will Dll

eliminate and

behavior the

D17

We

the

for

spectrometers

existence

at

both

t-ray

solutions

correlated

and

at

SAYS

was

regions

the

using

be very structure neutron con-

Prellnlnary

to S(q)_

it from

homage

several

Orsay.

be

without

will

to the

However empty

the

cell

a soeclal

measurements

1.L L. Grenoble.

of concentration of

patches

the measurements The

can con-

chemical

contrast

contrlbutlon

contribution.

region

the

at LURE,

to separate

to repeat such

ZnClB

source

angle

difficult

ordered

the

and

the

performed

radiation small

that

solutions

is sufficient

and

the ordering

have

obtained

as a function

probable

of

in the

there

range

be anticipated

to detect

It is thus

technique

served

the

of

contrlbdtion

data

oatches

provided

correlation

nature

it might

SAXS

centrations

the

dynamical

angle

ordered

scattering,

wlthln

be difficult

experiments.

range

angle

region

solutions

the

will

small

the

the

intennedlate

by

A sl9nsl

studied. extending

The

were was

ob-

results

over

ap-

proximately kes

these

30 to 40 i. results

only

However

in

this

qualitative

and

case

also

further

the weakness

more

precise

of

the effect

measurements

ma

are

needed. The probed

existence directly

time-of

Ih6

the

spectruneter

similarlty alfference

when

transformed density

inelastic

existence and at

of water

tial

nal

solute-connected

on

between

the EL3

soectrcmeter

the

solutions

water

water

cbserved

and

and

ZnC12

scale,

by Raman

More were show

of ZnCl

2 solution

and

spectra,

(see

the

ln the

fig.

Note

substanregion

3). intensity

is proportional

the dynamic

structure

tor S(w,q),

which

is the Fourier atomic

lation

which,

in the vibratlo-

scattered

I,,(w,q)

the

the

time-of-flight

and

The

in

on

respectively

to the maximum

spectroscopy

by

data-both

obtained

typical SrC12

be

qualitative-

precise

later

can

obtained

(12)

especially

soiutlon,

corresponds

data

at Saclay

vibrations.

SrC12

excitations

Preliminary

spectral regions(19) Grenoble In fig. 7 we

to an energy

of states

scattering.

of collective

saturated

between

vibrational

lnelastlc

1-L-L.

and

collective

neutron

spectroscopy

quasi-elastic

spectra the

by

flight

ly confirmed the

of

to fac-

in turn

transform

position

function.

of

corre-

Outside

the quasi-elastic

scatte-

nng

region (i.e. for w -1 ln our case) such 5 cm correlation lated

to the

bratlonal

(cl

function

collective

excitations

the

system.

the

experimental

In fact

it IS possible the

Fig.

7. Time-of-fllghz

neutron

scattering

spec

tra of (a): pure D20, (b) ard (c). saturated solutions of WC12 and ZnC12 in D20 respectively.

vibrational nal modes

v' of

from

spectrum to obtain

generalized

distribution

TIME OF FLiGtiT,psec/m

1s re -

frequency

Z(w) and of the

of

the

traslatiosystem

by

the

Egelstaff

extrapolation

Z(w) 2

llm w2/q2 q-0

Outside

of

the quasi-elastic

density

of

states

procedure

IN(d,q)

g(w).

(4) region,

In fig.

(D20)

and

for

trations

Note

the

progressive

the main

features

existence

of

compleves

dynamically

flrrned by

the

The

peak

most

prominent

tlon

of

in the

confIrms

work

of

ring

that

bonded

tl;e solute

or

lndlcate

the dlffus~onal

notion

position

solution The ted

of

durable cm

ZnCl

breaking

local

-1

increases

water

on

the band

gued

by multicomponent

ther

"species"

wing

our of

tlonal

density

ce of

the

found

that

ansatz

frequency

Raman

curve

of weter

general

of

shape

OH band

the overall

of

In aqueous bandsnaoe

of

solutions

the

the

of ZnSr2

be reproduced

ner:

to be

neutron

for

also

vibrations

scacteof

a saruratcd

coordlna-

produce

consl

in r;he 3400

nlstorically from

been one

pla-

or ano-

the

real llauyd (1) Foils -1 band as a whole, as cn

frequeficy

carefully

local

not

tert-ahedrally should

3100

low

the

dire-

In a quas'-aqua-

stenzI?ng

UD

mo-

parametrliatlon time

has

the

result

hor>ever

to 10 psec

band

to make

followed

could

Hz0

component

to consider

+!e have

(15)

solute

broad

each

band

con-

dramatically

quas;eiastic

the OH strechlng

we

side

ionic

translational

This

are

residence

the

thought

prefer

the

the

directly

destroy

r;he consequent

comoler

flttlng,

Thus

water,

decreases

molecules

oure

molecules

modulated states.

of

of such

corresoond

of

of oure

to the

oeaP

-SJolander

for

actlon

soectruq

,ncoherent

and

DU

concen-

system

stands

to saturation

aolecular

bonjs

by the

analysis

The

a sort

nydt-ogen

structure

effects

region

2 up of

which

same

concentration

Such

our

2 3sec

for

saturation

range

IS due

UD

a qlven

- in a Slngwl

from

the

vibrational

determined

the vibrations

This

increases

- the average

true

data

spectra,

in fact

that

of

with

in the

molecules.

the

at energies

lncermedjate

molecules

above

water

isolated;

(U)

librium

connected

to

3Y, 6Y and

soectrum

60 cm-')

water

at

of peaks

scattering

(ce.

reduce

exoerimentally

In D20

In the neutron

bonded

free

aata

Z(w)

some

as concentration

hydrogen

consIdered

7 meV

show

Ranan

over

neutron

feature

solutions

reduced

excitations

inelastic

should

increase

ordered

hydrogen

ctly

the

collective

at about

the

ZnC12

in

3 we

Z(w)

solutions

re water

to

(13)

nydrogen

the concentration (and very

also well

bond

dependen -

CuBr,), by

vibra-

linear

and super-

248 position tal

of

origIna

tb2

water

spectrum

and

the

soectrum

of

the

hydrated

crys-

(16).

The

Raman

evidence and

that

Cu6r2

phous

have

over

The

water

solute,

make

produce

of

in such

elastic

large

viewed

local

solid

the

dence

to the

as shcwn

Raman

long

contrlbutlon of

data

the

show

in the of

the

dlfflculties

The

water

and

solute

reupon

the

basic

frequency

The

structural

effects tion

of

(18).

tition

tuo

of

hydrogen

becomes

dominated

arising

time)

low

ratlo, peak

This

solute the from

EYPFS the

the

range

to the

Quasi mole-

Raman

region

is best

hydrogen

interpretation and same

freouency

concentration

by the

of

the

rest-

order

of

vlbratlons

of 2 to 3M,

IS demonstrated soectra

neutron

the

1lCe

due

The

local

in its

are

of

the water

bond

the

to re-

and

whe by

the

scattering

digene-

dlstributlon. and of

the local

tenuation

of

IS increased.

associated

to a typical

the

on some

dependence

up

Ram3n depolarization -1 the 60 cm hydrogen bond

ralized

influence

structure

is added

structure

of

time

for pure water the hydrogen bond liieilme

as

time

complexes.

fact

persist

tends

dominates,

with

extends

photon

Most

magnitude.

sappearance

residence

cornected

relaxation

of

collective

ir-

complexes

that

residence

anionic

lcfw frequency

states

anionic

symmetry

solute

and

concentration

as a structural

behavior

the

systems

dynamically

of water. tha+

of

the

that

as solute

density

of

of amor-

particle

range

The

to allow

cationic

and

local

the

by EUFS

(intended

the

time

a correlation

in which

to that

becomes

cationlc

conclusive

such as ZnC12

as many

with

itself

as a vibrational

due

similar

be vieweo

structures

IS sufficiently

water

IS very

mJst

the

and

provide

II-I electrolytes

with

solute,

consldelably

structure

which

presented

together

polar~rablllty

of pure

have

strong

they

distances,

scattering

increases

we

between the various components

structures

neutron

spectrum

bond

the

in which

relatively

thus

molecules, up

of

dynamics

context

inter-ionic

that

vlbratlors,

cules

solutions

a vibrational In this

several

Ions

scotte-c. .ng data

the distlnctlon

relevant. of the

neutron

tne aqueous

solids.

in which

are

and

dynamIca

e ffects

the macroscopic structural

change

the viscosity

In both

cases

structures,

have

oroperties

of both

the

we

data

t!:e water

at ca. (17)

and

may

be

strucutre

discussed of

the

so far

ultrasonic

interpreted and

tne

Ve

solutions

2Y concentration the

should

have

have

an

found

In the concentra velocity

in terms

solute-induced

of

and the

atcompe

structure

349

HOW

much

of

electrolytes

this

not mean

will

not

tuation.

the on

and

and

there

basic

ansatz

should

the

by neutron

function

classic single

we

we

have

concepts ion or

chemical

feel

ionic

that

as

physics

Instance,

apply;

Perhaps

scattering

and

high

phenomena

may

ions.

Ranan orecise

This

spectroscopy detennina-

to clarify

the

concentrations,

ln all

hydration

and

other

strong

shells, and

be more

si-

in the electroly-

or even

the

llquld

solute-related

complex

help

Irrelevant,

may become

of collective

new

to other

the

however

would

possibly and

be apolied

to form

not

probe.

solvatlon

complex

for

at sufflclently

studied,

such

may

1s no tendency

sensltlve

Z(w)

concepts

electrolytes

be a sufflclently

solutions

the

our

In any case

aqueous tes,

that

results

In I-I

1s small

dces

of

of

in general?

polarlzablllty

tions

body

that

analysis

of

based

aoproprlate

and

fruitful. An

obvious

ly aqueous standing

case

of applicability

solutions of

ve profound from

the

tein

(electro

the

of

proteins

interplay

blologlcal

oeglnnlng

the

yte)

1s that and

between

other

local

lmpllcatlons, collective

lnteractlons

polyelectrolytes,

blologlcal

structure

and

of

the

be most

and

polymers.

and motlonal

certainly

nature should

of

an aoproach

ohenomena

partlculay

Here

the under-

dynanllcs hhlch

may

ha-

stresses

assoclatedL&

ha&r-

pro-

fruitful

REFERENCES For genera background, see articles by G.Halrafen and and 3 respectively of "ilater a comprehenslve treatise" Plenum, N.Y

T H.Lilley

See

S Petruccl

(ed

), Academic

Press,

R Shuker and R-X Gammon, Phys.Rev.Lett. 25 (1970) 222 II H.Grodsky in "Light scattering in solids", pl Cardona lln, 1975, and references therein

(Ed

). Sorlnger,

Eer-

also

D E Irish

ln

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F rranks

in vols

1

(ed.).

N.Y.,1971

J H-R-Clarke in "Advances ln Infrared and Raman spectroscopy", J.H R-Clarke and R-E Hester (Eds.), Heyden London, 1978 M.P.Fontana, G Malsano, P Mlgllardo and F Wanderllngn, Solid State Corm 23 (1977) 489. F.Allotta, G Malsano, P.Mlgllardo and C Vasl, F 'fanderlln9ti, G 'Jedro Smlrh and

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M.P.Fontana,

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Phys.

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75

(1981)

P tilgllardo

615 and

F Wanderllngh,

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Chem

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69

(1978) 676 19 (1978) 289, P Elsenberger and 5.M hincaid, See e.g. E A-Stern, Cont.Phys. Science 200 (1978) 144 P.Lagarde, A-Fontaine, D.Raoux, A Sadoc, P.bligllardo, J Chm~ Phys. 72 (1950) 3061, A-Fontaine, P.Lagarde, D Raoux, M.P.Fontana, G Malsano, P Mlgllardo and F.!landerlingh,

Phys

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504.

250

9

10 11 12 13

14

is 16 17

18 19

G.Galll,

G.Maisano,

P.Higliardo,

C.Vasi,F.Wanderlingh.H.P.Fontana,Sol.St.Comm

42 (1982) 213; F.Aliotta, G.Galli, G.Malsano, P Mlgllardo, C.Vasi and Wanderllngh, Nuovo Clmento 2D (1983) 103. A.Guinier and G.Fournet, “Small Angle Scattering”, !Qley, N.!. 1955 G .bla I sane , P Migliardo, F.Wanderlingh, N.P Fontana, H-C.Bellissent-Funel and M-Roth, Solid State Corrm. 38 (1981) 827. Pl.P.Fontana, P.Higliardo, H-C.Bellissent-Funel and R.Kahn, SolId State 36 (1980) 541.

F.

COITITI.

P A.Egelstaff ln “Inelastic Scattering of Neutrons in Solids and Liquids”, p. 25, IAEA Vienna (1961); also P.A.Egelstaff, Rep.Progr.Phys 29 (1966) G.Yaisano, P.Hlgliardo. F.Handerllcgh, ‘1.P Fontana, Il-C.Sellissent-Funel, R-Kahn and A.J.Dianoux, to be published in Mol.Physics K.S.Slngwi and A.Sjolander, Phys.Rev 119 (1900) 863. F.Allotta, ll.P.Fontcna, G.Maisano, P.lllgllardo ard F.Wanderllngh. Optlca Acta 27 (19EO) 931. G.Maisano, P.Migliardo, 5596. G.Carlni , M.Cutroni, SolId State Phys. 13 M-C.Belllssent-Funel, sano and F.Wanderllngh,

F.Wanderllngh G.Plaisano,

and

M.P.Fontana,

J.Chm.Phys.

68

333

(19i6)

P.Migliardo and F Wanderllngh, J.Phys.C (1980) 967. R Kahn, A J Dianoux, Y.P Fontana, P.Mlgliardo, G.MaiManuscript in preparation