Tiêu chuẩn iso tr 18394 2016

This Te hnical R ep rt pro ides guidel nes for the identif ication of chemical efe t on X-ra or ele tron-ex cit ed A ug er-ele tron spe tra an for using these efe t in chemical charact e

Surfac e chemical anal ysis — Aug er

An lyse chimique des surfce s — S ec trosco ie de s électro s Au e

— Déduction de l’infrmation chimique

Refer ence n mb r

ISO/TR 1 3 4:2 16(E)

S con edition

2 16-0 -0

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© ISO 2016, P blshed in Sw itz rlan

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written permis ion Permis ion c n be req esed from either ISO at the ad r es below or ISO’s member bod y in the c u try of

F reword i v

Introduction v

1 Sc ope 1

2 Nor mati ve r eferenc es 1

3 Terms and definitio s 1

4 A bbreviated ter ms 1

5 T ypes of chemical and sold-state efects in Aug er -electr on spectra 1

6 Chemical efects ar ising fr om c ore- evel Aug er -electr on transitions 3

6.1 General

3 6.2 Chemical shifts of Aug er-ele tr on ener g ies 3

6.3 Chemical shifts of Aug er p ramete s 4

6.4 Chemical-s ate plot 6

6.5 Datab ses of chemical shifs of Aug er-ele tr on ener g ies an Aug er p r amete s 7

6.6 Chemical efe t on Aug er-ele tr on satel testructur es 7

6.7 Chemical efe t on the relative intensities an lne sha es of CC Aug er-ele tron lnes 8

6.8 Chemical efe t on the inelastic r eg ion of C CAug er-ele tr on spe tra 9

7 Chemical efects o Aug er-electron transitions invol ving valenc e electr ons 10

7.1 General 1

7.2 Chemical-s ate-dependent lne sha es of C V an CVV Aug er-ele tron spe tra 1

7.3 Information on local ele tr onic s ructur e from analysis of C V an CVV Aug er-ele tr on lne sha es 1

7.4 No el te h iq es for o taining information on chemical b n ing fr om Aug er pr oc s es 1

Biblog raphy 21

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ele trot ech ical s an ardization

The proc d r s used t o develo this document an those int en ed for it furthe maint enanc ar

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dife ent ty es of ISO document should be not ed This document was draft ed in ac ordanc with the

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on the ISO ls of p t ent de larations r c ived ( e www.iso.org p t ent )

Any trade name used in this document is information given for the convenienc of use s an does not

cons itut e an en orsement

F or an ex lanation on the meaning of ISO spe ific t erms an ex r s ions r lat ed t o conformity

as es ment, as wel as information a out ISO’ s adhe enc t o the WTO principles in the Te h ical

Bar ie s t o Trade (TBT), se thefolowing URL:F or word — Sup lementary information

The committ ee r sp nsible for this document is ISO/TC 2 1, S rf c e chemic al a alys i s , Subcommitt ee

SC 7, Elec tro s pec tros c opies

This se on edition canc ls and r plac s the firs edition (ISO/TR 1 3 4:2 0 ), w hich has be n

t ech icaly r vised

This Te hnical R ep rt pro ides guidel nes for the identif ication of chemical efe t on X-ra or ele

tron-ex cit ed A ug er-ele tron spe tra an for using these efe t in chemical charact erization

A ug er-ele tron spe tra contain information on surface /int erfac elemental comp sition as wel as

on the environment local t o the at om with the initial cor hole

[1][2][3][4][5]

Chang es in A ug er-ele tron

spe tra d e t o alt erations of the at omic environment ar cal ed chemical (or sold-s at e) efe t

R eco nition of chemical efe t is ve y important in pro e q antitative a plcations of A ug er-ele tron

spe trosco y an can be ve y helpful in identif ication of surfac chemical spe ies an of the chemical

s at e of cons ituent at oms in surfac or int erfac la e s

Surfac e chemical anal ysis — Aug er electron spectrosc opy

This Te hnical R ep rt pro ides guidelnes for identifying chemical efe t in X-ra or ele tron-ex cit ed

A ug er-ele tron spe tra an for using these efe t in chemical charact erization

2 Normati ve r eferences

The folowing document , in w hole or in p rt, ar normatively r fe enc d in this document an ar

in ispensa le for it a pl cation F or dat ed r fe enc s, only the edition cit ed a pl es F or u dat ed

r fe enc s, the lat es edition of the r fe enc d document ( inclu ing any amen ment )a pl es

ISO 1 1 5 (al p rt ), S rfc e chemic al a alys i s — Voc ab lar y

3 Terms and definitions

F or the purposes of this document, the t erms an def initions given in ISO 1 1 5 (al part ) a ply

4 Abbr eviated ter ms

C C cor -cor -cor (A ug er-ele tron transition)

C V cor -cor -v lenc (A ug er-ele tron transition)

CVV cor -v lenc -v lenc (A ug er-ele tron transition)

DEAR-AP CS Dichroic Efe t in Angle R esolved A ug er-Phot oele tron C incidenc Spe trosco y

h-BN hex g onal b ron nitride

IAE Int erat omic A ug er Emis ion

ICD Int erat omic C ulomb De a

PAES Positron-An ihiation-in uc d A ug er Ele tron Spe trosco y

REELS R efle tion Ele tron E e g -L s Spe trosco y

5 T ypes ofchemical and sol d-state efects in Aug er-electron spectra

Many ty es of chemical or sol d-s at e efe t can be o se ved in A ug er-ele tron spe tra

[1][2][3][4][5]

Chang es in the at omic environment of an at om ioniz d in it in e shel can r sult in a shif of the kinetic

ene g of the emitt ed A ug er ele tron In the case of X-ra -ex cit ed A ug er-ele tron spe tra, ene g shifs of

A ug er p ramet ers ( i.e kinetic -ene g dife enc s between A ug er-ele tron peaks an the phot oele tron

peakscor esp n ing t o the cor levels involved in the A ug er-ele tron proc s ) can be det ect ed as wel

Furthe mor , the lne sha e, the r lative int ensity and the sat el t e s ructur ( in uc d b the intrinsic

ex citation proc s es) of the A ug er-ele tron l nes can be conside a ly influenc d b chemical efe t ,

as can the s ructur of the ene g -los r gion ( in uc d b extrinsic, ele tron-scatt ering proc s es)

ac omp nying the intrinsic peaks Strong chemical efe t on the A ug er-ele tron spe tral sha es ofe

way s of identification of chemical spe ies using the “fing erprint” a pro ch

In the case of ele tron-ex cit ed A ug er-ele tron spe tra, the A ug er peaks ar g ene aly weak featur s

supe imp sed on an int ense backgroun caused t o a larg e ext ent b the primary ele trons scatt er d

inelas icaly within the sol d sample As a conseq enc , the dife ential A ug er-ele tron spe trum is

oft en r corded (or calculat ed from the measur d spe trum) rathe than the dir ct ene g spe trum,

faci itating the o se v tion an identification of the A ug er-ele tron peaks an the measur ment of the

r spe tive A ug er transition ene gies Dife entiation can, howeve , enhanc the visibi ity of ran om

fluctuations in r corded int ensities, as shown in Figur 1 If chemical-s at e information is ne ded from

a dir ct ene g spe trum, then the r lative ene g r solution of the ele tron spe tromet er should be

bett er than 0,1 % (e.g 0,0 % or 0,0 % ) A p or r ene g r solution causes a significant bro dening

of the A ug er-ele tron peaks and pr vent o se v tion of smal chang es of spe tral lne sha es or peak

ene gies as chemical-s at e efe t in the spe tra A gr at adv ntag e of ele tron-ex cit ed A ug er-ele tron

spe trosco y o e X-ra ex citation with la orat ory X-ra sour e, however, is the p s ibi ity of using

high lat eral r solution an o taining chemical-s at e ma s of surfac nanos ructur s

NOTE 1 A ug er -electron spectra can b report ed with the energy s ale referenced either to the Fermi level or

t o the vacu m level Kinetic energies with the latt er reference are ty icaly 4,5 e V les than those referenced to

the F ermi level, but the diference in energies for these two references can vary from 4,0 e V to 5,0 e V since the

position of the vacu m level depen s on the con ition of the spectromet er an may, in practice,vary with respect

t o the Fermi level When energy shif s are det ermined from spectra recorded on diferent instruments, use of

diferent energy references should b taken int o ac ou t

NOTE 2 While the visibility of noise fe tures in a diferential spectrum can b red ced by use of a larg r

n mb r of chan els in the calculation of the derivative, there may also b dist ortion of the resulting diferential

spectrum an los of f ine details as ociat ed with chemical-stat e efects

Key

X kinetic ener g y, eV

Y intensity

1 difer ential spectrum

2 dir ect spectrum

NOTE This f igure is reprod ced from Figure 2.8of R eference [1]

Figure 1 — C mparison of direct and dif erentiat ed A ug r-electro spectra for co per (Cu

LMM pe ks)

6 Chemical efects arising fr om core-level Aug er -electron transitions

Cor -level (or cor -cor -cor , CC ) A ug er-ele tron transitions oc ur w hen al of the levels inv lved in

the A ug er transition belong t o the at omic cor for the at om of int er s

6.2 Chemical shif s of Aug er-electron ener g ies

The main efe t ofany chang e in the sold-s at e environment on A ug er-ele tron spe tra for A ug er

transitions inv lving cor levels is a shif of the Aug er ene gies This shif r sult from a chang e in the

cor at omic pot ential d e t o the chang ed environment an from a contribution d e t o the r sp nse of

the local ele tronic s ructur t o the a pearanc of cor holes A ug er chemical shif s ar g ene aly larg er

than the bin ing -ene g shifs of the at omic levels inv lved in the A ug er-ele tron proc s be a use the

two-hole final s at e ofthe proc s is mor s rongly influenc d b r la ation efe t This phenomenon is

i lus rat ed b the ex mple of aluminium an it o ide in Figur 2

[6]

L rg e chemical shif s in the ene g

positions of the A ug er-ele tron lnes pro ide p s ibi ties for chemical-s at e identification even in the

case of ele tron-ex cit ed A ug er-ele tron spe trosco y with, in this case, mode at e ene g r solution In

X-ra -excit ed A ug er-ele tron spe tra, the peak-t o-backgrou d int ensity ratios ar usualy larg er than

those in ele tron-excit ed spe tra, faci tating ac urat e det ermination of peak ene gies R ecommen ed

A ug er ele tron ene gies ar av aia le for 42 elemental sol ds

[7]

Information on A ug er chemical shif s of

particular element can be o tained from han b oks

Figure 2 — Photoelectro and A ug er-electro spectra of an aluminium foi co ered b a thin

o erlayer of aluminium o ide: Ex citatio with Al and Mo X-ray s

W ith the adv ntag e of high-ene g -r solution analy se s, smal chemical shif s of A ug er-ele tron lnes

d e t o dife ent y e of do ant in semicon uct ors be ome disc rnible (for ex mple, the kinetic -ene g

dife enc betwe n Si KL peaks from n-ty e an p-ty e si icon is 0,6 e V

[1]

), alowing chemical-s at e

ma ping in spit e of the extr mely low conc ntration (far below the det ection lmit of A ug er ele tron

spe trosco y) of the do ant Figur 3 shows a Si KL A ug er-ele tron ma de ived from a c os se tion

of a p-ty e si icon sample do ed with phosphorus b implantation t o o tain n-ty e Si at the sample

NOTE 2 T is f igure has b en reprod ced from Figure 5.3 of R eference [1]

Figure 3— Si ico KLL A ug er-electro map of a p-ty e si ico sample implanted with

ph sp orus to pro uce n-ty e Si at its surface

6.3 Chemical shif s of Aug er parameter

A ug er p ramet ers, o tained from X-ra -ex cit ed A ug er-ele tron spe tra, can also be s rongly influenc d

b the environment of the at om emit ing phot oele trons an A ug er ele trons

[2][14][1 ][16][17][18]

The

A ug er paramet er, α, is given b F ormula (1):

α =KE(jkl)−KE(i) (1)

w he e

KE(jkl is the kinetic ene g of an A ug er transition inv lving cor levelsj, k a d l of an at om;

KE(i is the kinetic ene g of a phot oele tron from cor level i (w hich ma be the same as the

cor level j

In orde t o a oid neg tive v lues of the A ug er p ramet er

[14][1 ][16]

themodified A ug er p ramet er, α′ is

used in mos practical cases The modif ied A ug er paramet er is given b F ormula (2):

is the ex citing phot on ene g ;

BE(i is the bin ing ene g of an ele tron in the cor level i

It is also pr fe a le t o use α′rathe than α be ause the v lue of α′is in epen ent of E

p

The A ug er p ramet ers can be measur d even in the case of s atic charging, sinc any charging shif is

canc led as ene g sep rationsof peaks ar det ermined No ene g -r fe encing pro lems oc ur

[14][1 ]

in the case of measuring A ug er paramet ers; i.e data o tained using the v cu m level asr fe enc can be

comp r d dir ctly t o data o tained using the F ermi level as r fe enc A ug er p ramet ers can the efor

be ve y useful in the charact erization of insulat ors an semicon uct ors, w he e the ene g p sition of

the F ermi level of the sample is not wel defined A chang e in the at omic environment of a cor -ioniz d

at om can r sult in a chemical shif of the cor espon ing A ug er p ramet er A ug er-paramet er shif s

depen on dife enc s in the v lenc charg e in the initial grou d s at e an in the f inal s at e (

intra-at omic contribution), as wel as on dife enc s in the contribution t o the r la ation proc s of al othe

at oms in the sy st em (extra-at omic contribution)

[16]

When the intra-at omic contribution is dominant, a local sc e ning me hanism of the cor hole takes

plac , w hie in the case w hen the extra-at omic contribution is dominant, the sc e ning me hanism is

as umed t o be non-local In the latt er case, simple ele tros atic models can be used for es imating the

ele tronic polarization ene g

[5][16][17][18][1 ][2 ]

The model of Mor t i

16]

desc ibes the f inal-s at e

polarization proc s in w hich the sum of the ele tric f ields (at the lg n s) is g ene at ed b the c ntral

positive charg e an b in uc d dip les on the lg n s in the f irs co rdination shel This model can be

a pl ed t o es imat e the extra-at omic p larization ene g an the A ug er-p ramet er shif s Calculation

of A ug er paramet er shif s using the ele tros atic model of Mor t i is faci itat ed b the p s ibi ty of

a plying the fr ely a aia le Tinker mole ular model ng an Molden comput er gra hic sof war

packag es

[18]

Weightman, et al

[2 ][2 ]

develo ed a dife ent model, the “ext ended p t ential model” ,

for es imating the A ug er-paramet er chemical shift ; pot ential p ramet ers we e de ived from at omic

calculations an theangular-momentum charact er of the ele trons was taken int o ac ou t This model

gives a g ood a pro imation in the case of larg e charg e trans e in the final s at e (con uct ors), w he e

the ele tros atic model is not a plca le, an desc ibes wel the local sc e ning me hanism In thecase

of binary aloy s, thema nitu e of the trans e r d charg e can be ac urat ely de ived

[3]

A r view on firs

principles calculations of A ug er kinetic ene g an A ug er paramet er shif s in metal ic bulk solds from

the density functional theory ar discus ed in R efe enc

[2 ]

In the case of nano articles, the A ug er p ramet er can depen on the siz of the p rticles Figur 4

show s the depen enc of the A ug er p ramet er of Cu nanoclust ers [deposit ed b ev p ration ont o highly

orient ed pyroltic gra hit e (HOPG)] on the nominal thick es of the Cu la e

[24]

It was fou d that the

Cu A ug er paramet er depen s lnearly on 1 d, w he e d is the a e ag e diamet er of the Cu clust ers

[24]

NOTE S e Figure 2of R eference

[2 ]

Figure 4 — Dependence of the Cu A ug er parameter o the nominal thicknes of the C laye

co sisting of C cluster deposited by evap ratio o to HOPG surface

6.4 Chemical state plots

F or chemical-s at e identif ication an A ug er-p ramet er analy sis, the pr sentation of A ug er p ramet ers

in the form of a two-dimensional plot, as pro osed b Wa ne , pro ed t o be ve y useful

1 ]

The A ug

er-ele tron kinetic ene g is in icat ed on the ordinat e of the plot an the cor esp n ing phot oele tron

bin ing ene g is on the a scis a but orient ed in the neg tive dir ction, as shown in Figur 5; cons ant

A ug er-p ramet er v lues ar r pr sent ed on the plot b a s raight lne with a slo e of – (not e that the

a scis a a is in Figur 5 is inc easing t o the lef) In the case of a neglgible chang e in the intra-at omic

r la ation ene g (d e t o the v rying at omic environment), the chang e in the extra-at omic -r la ation

( final-s at e-efe t) ene g dominat es, an comp nent with highe extra-at omic r la ation ene g

le in the up e part of the chemical-s at e (or Wa ne ) plot On the othe han , w hen the initial-s at e

efe t (pro ortional t o the sum of t erms r lat ed t o the groun -s at e v lenc charg e an the Madelu g

pot ential) dominat e, the slo e be omes – on the chemical-s at e plot ; i.e chemical s at es with simiar

initial-s at e efe t le on s raight lnes with a slo e of – This r sult i lus rat es that chemical-s at e

plot can be analy sed t o pro ide information on the natur of the chang es in the environment of the

chemical-s at e plot can help t o dis inguish between chemical s at es not sep ra le on the b sis of cor

-level bin ing ene g shif s or A ug er-ele tron-ene g shifsalone

X Sn 3d

5 2bin ing energ y,eV

Aug er parameter +p oton ener g y

NOT R eprinted from R eference

[2 ]

Figure 5 — Chemical state plot for tin comp unds

6.5 Databases of chemical shif s of Aug er -electron ener g ies and Aug er parameter s

The f irs compr hensive set ofc itical y cole t ed data on A ug er p ramet ers, A ug er-ele tron kinetic

ene gies an phot oele tron binding ene gies for seve al element is foun in R efe enc

[1 ]

A han b ok

contains a cole tion of ex e imental phot oele tron bin ing -ene g an A ug er-ele tron kinetic -ene g

data for a larg e n mbe of comp un s

[8]

an inclu es seve al chemical-s at e plot The lat es ve sion

of the US National Ins itut e of S ienc an Te h olo y XPS Data ase

[1 ]

pro ides onlne ac es t o

o e 3 0 0 r cords of phot oele tron an A ug er-ele tron data inv lving int ense transitions for mos

element an many comp u ds This data ase sup les A ug er p ramet ers, has the o tion of displa ing

chemical-s at e plot , and is ve y useful for identif ication of chemical s at e as wel as in s u ies of the

depen enc of polarization ene g on chemical s at e A ug er-p ramet er v lues for 42 elemental solds

ar r commen ed in R efe enc

[26]

6.6 Chemical efects on Aug er-electron satel ite structures

A ug er-ele tron peaks can be ac ompanied b sat el it e lnes d e t o intrinsic ex citations These

ex citations ar oft en of at omic origin As a conseq enc of the c eation of the cor hole, ele trons can

be ex cit ed from oc upied levels t o u oc upied s at es ( hake-up) or t o the contin um ( hake-of ); the

A ug er-ele tron proc s then takes plac in an ex cit ed or multiply ioniz d at om Not e that not only the

shake-up but the shake-of proc s r sult in a pearanc of sat el t es in A ug er-ele tron spe tra, in

contras t o phot oele tron lnes w he e the shake-of proc s in uc s a contin ous ene g contribution

t o the spe trum The ex cit ed ele tron can be eithe a spe tat or or a p rticip t or in r lation t o the

A ug er transition In this latt er case, the ene g of the A ug er sat el it e can be even highe than that of

the main l ne Figur 6 show s an extra rdinariy int ense sat el t e oc ur ing in the F KL spe trum of

p lyc y stal ine KF ; this sat el it e is int erpr t ed as a r sonanc betwe n the groun s at e an the cor

-ioniz d s at e

[27]

C upl ng of u pair d spins in the ioniz d cor level an in the out er shel leads t o

multiple splt ing of A ug er lnes;these splt ings can be afe t ed b chang esin the at omic environment

as wel

Key

X kinetic ener g y, eV

Y intensity

Figure 6 — S telite structure (designated by ar ow s) in fluorine KL A ug er-electron spectra

of flu rides

6.7 Chemical ef ect s on t he relat ive intensit ies and l ne shapes of CCC A

uger-elect ron l nes

The r lative int ensities of C C A ug er-ele tron transitions ma chang e as a r sult of dife ent A ug

er-transition pro a i ities in dife ent at omic environment

[28][2 ]

Ve y fas C st er-Kronig (CK) proc s es

taking plac prior t o a p rticular A ug er transition can conve t the initial cor hole int o a v cancy in a

cor level with a smale bin ing ene g , leading t o a conside a le chang e in the r lative int ensities of

A ug er transitions inv lving levels that p rticip t ed in the CK proc s The pro a i ity of these CK

proc s es can s rongly depen on the chemical environment

[3 ]

In the case of some metals, C C A ug er

l ne sha escan be s rongly asymmetric d e t o ele tron-hole p ir ex citation in the con uction b n

[3 ]

F or adsorb t es, a conside a le bro dening of the A ug er-ele tron lne can oc ur as a conseq enc of

phonon ex citation b the a pearanc of the cor hole

[3 ]

6.8 Chemical efects on the inelastic reg ion of CCC Aug er -electron spectra

Strong v riations in the ene g -los s ructur of A ug er-ele tron spe tra can be o se ved, folowing

chang es of chemical s at e, e.g in the case of some fr e-ele tron metals an their comp un s Figur 7

show s the dife enc betwe n the KL A ug er spe tra of metal c Al an Al

2O

3[34]

R efle tion Ele tron

Ene g L s Spe trosco y (REELS) can be used t o conf irm an sep rat e chemical-s at e-depen ent

ene g -los s ructur s in A ug er-ele tron spe tra On the othe hand, the int erpr tation of REELS

spe tra of multi-comp nent syst ems can be conf irmed b the surfac chemical comp sition, o tained

from q antitative A ug er analy sis

Figure 7 — Aluminium KL A ug er-electron spectra o tained by photo-ex citatio with Zr X-ray s

from an o idized sample (lowe curve)and after various times of io sputt ering to remo e the

o ide (uppe curves)

7 Chemical efects on Aug er -electron transitions invol ving valenc e electrons

In the case of A ug er transitions inv lving v lenc ele trons, the A ug er-ele tron l ne sha es ar ex e t ed

t o chang e d e t o chang es in chemical s at e The det ection of these lne sha e chang es ma r q ir high

(bett er than 0,5 % )r lative ene g r solution, although the chang esar o se v ble at mode at e ene g

r solution in many cases

7.2 Chemical state-dependent l ne shapes of CCV and CVV Aug er-electron spectra

The l ne sha es ofcor -cor -v lenc (C V) an cor -v lenc -v lenc (CVV) A ug er-ele tron spe tra can

depend s rongly on theenvironment ( i.e the chemical s at e) of the at oms emit ing the A ug er ele trons

This efe t can be uti iz d for fing erprinting, i.e for identif ication of chemical s at e Early measur ment

of carb n CVV A ug er-ele tron spe tra showed o vious dife enc s in l ne sha es for gra hit e, diamon ,

metal carbides and carb n mono ide adsorbed on a metal surfac

[36][37]

Figur 8 show s ele

tron-ex cit ed Si L

2

VV A ug er-ele tron spe tra of sold si con an of v rious si con comp u ds that show

conside a le dife enc s in lne sha es

[38][3 ]

Figur 9shows P M

45N

45N

45

A ug er-ele tron spe tra for

dife ent Cu-P an Ag -P alo s

VV A ug er-electro spectra in the dif erential mo e for sol d si ico an

vario s si ico compo n s