HAL Id: jpa-00227247
https://hal.archives-ouvertes.fr/jpa-00227247
Submitted on 1 Jan 1987
HAL
is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.
L’archive ouverte pluridisciplinaire
HAL, estdestinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
THE CVV AUGER SPECTRA OF CHLORO (METHYL) - SILANES IN GAS PHASE
M. Cini, F. Maracci, R. Platania
To cite this version:
M. Cini, F. Maracci, R. Platania. THE CVV AUGER SPECTRA OF CHLORO (METHYL) - SILANES IN GAS PHASE. Journal de Physique Colloques, 1987, 48 (C9), pp.C9-781-C9-784.
�10.1051/jphyscol:19879137�. �jpa-00227247�
THE CVV AUGER SPECTRA OF CHLORO(METHYL)- SILANES IN GAS PHASE
M. CINI, F. MARACCI and R. PLATANIA
Istituto di Metodologie Avanzate Inorganiche, CNR, Area della Ricerca d i Roma, C P 10, I-00016 Monterotondo, Italy
Rdcme'-Ntxff; p w s e n r m les spectl-es el&tronicpes expdrimentals CVV A q e r de C a h , Silicium et C h l o r ~ dans la s&fe (CH3)nSiC14_, [n=0,4j. Pour le membre de se'rie avec n=4, nwc; avons fsit t ~ 1 plus une analyse thebriqu~! de la forrne spectrale qui permet de comprmjre i s s t r c t u r e s principles sans calcuis trop &endus et sans paramares ajustables.
B,hstract-The experimental CVV Auger electron spectra of Carbon,Sllicoo and Chloriix in the series (CH3lnSiClq-, In=0,41 are raporkd. For the n=4 member of the series we also provide a t h r e t i c a l analysis of the Iiiiesha e that allows to understand thr main features without extensive computatim an8wit1-i no adjustable parameters.
Experbmta1.-The a ratus to obtain the electron impact excited Auger CW spectra was d e s c r f b z $~revfousl~ [ I ) . The spectra prosated hsm were measured with a 1860 eV, 70
A)
excltirg beam. The w r g y resolution was O.5eV.for the St spectra and l e v for6
and C1 tra. T~E energ soale was calibratsd using the Ar Llm3MM Auger tr-itions i n r r - e 200-2idleV and the KrMNN
translticm in t g k n g e 5 0 6 0 eV a m r d i to the procedure of Ref.111. The accuracy of the scale is estimated to b. about a??ev. All the spectra were taken a t an angle of 33' respect to the incident beam where the k tsignal-to-background ratio was found.Al1 t b data were subjected to b a d c g d subtraction[i].Results and discusslim.-In Fig.la,b and c we p r m t the ctra of all
the
members of the series. The Auger spectra of Cl and C mantain mu?? the same fingerprint , with fine structure d l n g 1 x 1 the specific molecule an52s
ovec-all line h a p e resembles the llC1 a M4 spectra respectively. S1 spectra exhibit a different t r m i and more dramatic variations can be chservxl a m q the various cumpow&. While tbetxettcal work on these p t r a fs in ~ " o g r ~ ~ s , b e we wish to present the Tetramethyl-S!!m (TMS) spectiurn amf.*av iwu a a-mparativeiy simple analysis allows to d e r s t a n d the l i r w c k ~ e r a h r well.The theory of Aqger C W lineshapes that we have used fix- TI\.fS is a direct e x h i o n of the one proposed by one d us long ago [3,4]. Within a normalization constant, the Auger current is given in terms of the danstty of statesD
of the two final hoies byJ =
2 2 f
XfL,,L.C~,WD
(4 (if,a L1L2 3L4 Li L2 L3 Lq"
where L c (1,m) demtes a single-particle orbital,
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19879137
C9-782 JOURNAL DE PHYSIQUE
F1g.f -.Auger spectra: a) L 3JV Chlorine b) KW Carbon c) L Z s 3 W S i l i m . The two-hole binding energy scales a r e r e f e r a d to L3, 253 K and L2,3 levels of Chlorine,Carbon and Silicon, respectively [2]
.
A a r e Au e r matrix elements,and the idices f a d c denote the Auger electron a d the h i t i a g a r r e state, twpxtively. % A's for C were wmpued using Mc Cuira's at~smic radial matrix elements 153; for Si we used the improved values given b Jerinim 161; t h e m M n g in J W s o n 5 s paper wre taken from Feibelman a n l ~ c Gutre [7]. Both atoms ha* s anti p valenm states, and the current (I) naturally d e c a m p s into mtributioos J(ss),J(spf, a d J[pp) a m d i n g to the nature of the final state holes. We have lected the slight mixing of s and s t a b which is allowed b s y m m e t y on t h 3 site; howeve- we have allowed
?
o r the midng of ss and pptwo-bores
states y the Coulomb interaction, which p r d w e s an interference contribution J[ss pf to i2-e current. The relevant two-holes Coulomb integrals were c o m p d using t& atomic wavefunations of Ciementi and Roetti 181 and were used to wo out the two-holes repulsion matrix W of Ref.[4]. However all the final state levels d e o a common electrostatic shift <U)-1/R, where R is the molecular size. ~ r o m x C-11 bond lsngth (1.049 A) and the Si-C Oad l q t h (1.873A) we obtain <U)-4.9 eV. Following Thomas and Weightman 191, we take <W to by a rigid shift of the spectrum a d subtract the same amount from the Coulomb elements d W. We a-suned M effect on the ex~+ange matrix e l e m e n t s . f i interacting Green's f m t t o n matrix G IPY given in terms of its indepwrdent-particle counterpart Ga by [4]Here, E is the m i t matrix in the space of t w o h l e s configurations. Finally, D -1mG.
Symmetry d t r c e s t b m a t r i m in block form and we reed not invert more than 4x4 determinants. Go is obtained a s a selfc(x1~3lution of the orehole Green's fmtion.
The latter was calculated from the experimental energy levels of TMS given by Jonas et al. (iO]. The a m t a g e f w m also gi.m by the w m e Authors and we d
P
thxa obtained by a se fuollsistent molecular orbital calculation. Fig.2 shows the exprlrnental results for S i compared with the independent-particle limit and with the full theory. The v t r u m is seen to be band-like,but h small distortion due to tkhole-hole interaction improves h agreement with experiment. The bind1 energies and relative intenstties of the main features are well m d d , a 3 we believe that the two peaks a t -46eV and a t -34eY.which are m%m out by the calculations, do rut actually belong to the m m a l C W transition. As suggested 6f
mental data [soliddotbd line). and the envelope of calculated peaks br0admec-f into Lorentzlans of
i .BeV FWHM in tk nontntemctlng [broken limI and Full t b r y (solid lim) a m shown. 7he twohole bfndiq energy scale Is referenced to the St L2,3 level [2].
Fig.3-Carbon KW Auger spectrum fn TMS.
Tk
experimental data(solid4otted linef and the envelope of calculated peaks broadened into Lorentzlans d i .8eV FWHM in the
~ n t e r a u t l n g [broken line). and full theory (solid 1im) are shown. Both the last two cunvolutions a r e shifted by 3eV to higher birding w r g y (see text). The two-hole binding energy scale 1s referenced to the C 1 s level 121.
C9-784 JOURNAL DE PHYSIQUE
P.\Eletghtrnan lprfvate communication), they are probably d w to three-holes final states p d m d by a
Li-L2-3V-V4V
CosterKmnlg satellite. Some of theexpertmental p a k s sh& a koorly r e s o l d doublet structure, prdxbly clue to h spin-orbit splitting of the cure iewl, not included here. Ff 3 r orts a slrnilar
ison of theory and experiment for t t s C spectrum. Rere,& dlstortlons d w to ol+hole Interaction a r e mere evident. Unlike the St case, the calculated curves
zmr'.
were shifted b 3eV towards the high birding mrB side to obtain a g m m m t with wperiment. d i s shift could be due to a limitation of the present model, which in princi le is 'ustifled for dosed &ells [2-41; b m v e r we b l i e v e it i s not too distur!irg.de experimental binding energies of th2 one electran lewls a r e
themselves difficult to ascertain to better than -ieV due to a large vibrmlc cwpliry:
and important Jahn-Teller distortions [i0]. On the other hand, we were able to reproduce the 17 fi erprint suite well, by an essentially awlytic calcwiatioo that motains m adjusr%e parameters. This enmurages us tu pursue a slrnilar analysis for the other spectra a s well. This work is currently under way.
i R.f.Cini,F.Wiar%cc:i and R.Platania.J.EI~tron Spechsc. Relat.PImm. 4 1,37 / f 986)
2-A.A.hkke,H. W . h and W.L.Jolly, J.Electron Spectrow. Relat.PFmm.20, 333 Lf (380)
3-M.Cini,%lid State Commm. 20,605 (1976) and 24,68 f If 977) 4-M.Qni,Ph . R ~ . B i 7 , 2 7 8 8 119781
~-M&ulre,$~s,.~ev 185,L (1964) 4-Ol.R.Jmison,Phys,Rev Bi8,6865 (19781
7-P.LFeifxlman and E.I.RIcCuire,Phys.R~v.B17,690 f f 978)
8-E.Clementi and C.Roetti,Atomic Data and Noclear Data Tables 14,177 (19741 9-T.5.Thornas and P. Weightman,Chem.Phys.Letters 3 1,325 (1 93 if
10.-A.E.Jow,C.K.Mweitzer,F.A.Crimm and T.kCarlson,
