- Email: [email protected]
Theoretical investigation of the sulphur K-LL auger energies and chemical shifts in a series of sulphur compounds
CHEhfICAL
Volume 69, number 1
THEORETICAL
INVESTIGATION
1
PH\ SICS LETTERS
OF THE SULPHUR K-LL
Januarq 1980
AUGER ENERGIES
AND CHEMICAL SHIFTS IN A SERIES OF SULPHUR COMPOUNDS Gmmoula THEODORAKOPOUL9S Deparrmrrrr of Ckrn~sr~
%. Imre G CSIZhlADlA
Unlr ersrr1 of Toronto, Toronto. Canada .V_5S I 1 I
and hhchael
A ROBB
Deparrrnenr o~~Clrcrmst~~ Queer Ekaberh Recewed
College, Londolr R’S 7AH, UK
1 August 1979
Tuo scrles of rnvestrganons arc reported on LL doublehole states oi molecules contammg sulphur. rust. the results on the LL double roruzat1on potentI& an-l ii-LL Auger energies oi Hz.5 and SO2 show that the use oi a irozen-orbrtal approw matron IS preferable to SCI methods for calculation of chemrcal shlits m K-LL Auger cnergles and LL ronlzauon potcnttals SecondI! chemrcal shafts of K-LL Auger energes of a senes of model molecules HzS HISO, HJSO~ and HzS02 are correlated ulrh the tormal o\ldatlon state of sulphur. This corrclatron Ewes a shaft of 11 eV m Auger energy per iormal charge on sulphur.
1. Introduction The effect of chemical bondmg on the energes of transmons mkolvmg inner-shell electrons has been studred rather eltenslvely for X-ray fluorescence and ESCA processes and to a lesser extent for Auger processes [l-31 The chemical shifts In the K-LL Auger energy (AE) of sulphur ha\e been correlated ~qth the formal charge on the atom [ 11, with the partial charge on S. as obtamed by population analysts and ab mltlo calcularlons on molecules [3], and wrth evpenmental ESCA shifts m the sulphur 2p lomzatlon potential (IP) [4]. The general trend IS decreasmg K-LL Auger energy with increasmg L shell IP [4] and decreasmg AE v.?th increasmg formal or partial charge on sulphur [1.3]. A tift of 16 eV per formal charge was predlcted by a theoretIcal study of K-LL Auger energy In the sulphur atom and posltlve ions [ 11. lhs result IS an overestlmatlon of the AE chemical shifts smce the formal
charge or oudatlon state in molecules IS not the actual charge on the atom as It IS m the free atom The ekpenmental values obtamed for molecules are much smaller than 16 eV: the Difference in K-LL AE between the two types of sulphur m NalS203 (S’-, S6+), is 4.3 eV [l], or about 0.5 eV per?orrnal charge. In the present paper. two series of investlgatlons are reported. First, the Inner-shell double-hole states of HZS and SO? are computed usmg multlconfiguratlon SCF (MC SCF) and CI methods which were proven efficient for the assqnment of valence-shell Auger spectra of H2S and SO2 [5,6]. The results on the LL double iontzation potentials and K-LL Auger energes are compared blth expenmental data [3], to test the vahtity of the theorerlcal models used. Secondly, calculatlons on the model molecules H,SO,H,SO, and H2S02 [7] have been performed to mvestigate the chemtcal stifts in the Auger energies as a functron of the formal sulphur oxidation state. 1. Theory
l
Present address Theoreucal Chemistry NatIonal Hellemc Research Foundatron,
66
The AthensSOl/l. Greece.
institute.
The L shell double-hole
states of sulphur
m mole-
Volume 69, number 1
PHYSICS LET-l-ERS
CHELIICAL
cules may be approximately classified usrng the atomic LS terms: IS (2s02p6), lv3P (2s12p5) and 3P, lD, IS (2~~2~~). In general, on restnction to a cubic group m the mclecule, the degeneracy wrll be shghtly broken. However, the wavefunctions wrll be very close to atomrc LS ergenfunctions that have been adopted for the relevant cubic group. Thus, for example, m CZv symmetry three states of symmetry 1A, ansmg from ‘D and 1 S (s2p4), retam the appro_xunate form
(1) ID IAl
= 6-i/2
(2
‘S IAl
= 3-ii2
PZ PZ - PX PX - P_v PJ) * -
(2) (3)
For thrs reason rt IS essential to use multrconfiguration methods. In the present work we have used the MC SCF method that has been drscussed prevrous!y [5]. In addrtron we have used the parent orbital configuratron Interaction (POCI) method (correspondmg to a frozen-orbital approximatron). In tlus method the double-hole configuratrons are constructed usmg the MO of the parent molecule and the double-hole states computed by dragonahzmg the hamrltoruan matrix of the doubly posrtrve ion over the double-hole configuratrons. The POCI method for double-hole states is analogous to usmg Koopmans’ theorem for smgle-hole states of molecules and it has been shown that the POCI method is useful in assqning the suIphur L-mm’ and the oxygen K-mm’
Auger spectra of SO2 [6]. The POCI total energy of the inner-shell hole states of molecules
double-
1s lugher than the SCF total
energy of these states and the difference IS a measure of the relaxation energy of double-hole states SCF _ E;OC’ E relax = ET
The contnbutron figuratron mteractron proxrmatron may be tween the eigenvalue onal matrix element dragonahzation (H,), Ecl=E,-H,,. I
_
(4)
to the total energy due to con(EC’) at the frozen-orbital apobtamed as the drfference be(E,) and the correspondmg dragof the hamrltonian matrix before
(5)
3. Results
I January 1980
and discussion
3.1. AfC SCF and FOCI calculntiotts on H$
and SO,
PoCl and MC SCF calculations were carried out on the L shell double-hole states of H2S using a doublezeta basrs set augmented wrth floating p functions as m ref. [5] _ For SO,, calculations have been carried out only at the POCI level (the basis sets are as reported in ref. [6]). To rIlustrate the general form of the rest&s obtained in the calculations we give the MC SCF and POCE results on H2S m some detarl m table 1_ These data are typical of those obtamed for the other sulphur-containing molecules studred m thrs work. From an inspection of column 1 of table 1 (leading electronic configuratron), we confirm that the eigenfunctions FolIow the LS couphng scheme (compare lines 5,7, and 9 with the LS couphng coefflcrents in eqs. (l), (2j and (3)). The configuratron-mteraction contribution to the total energies is generally smaU (cf. EC1 column in table l), except for the IAl states m the LD and tS terms. The relaxatron energy (Erelau in table I) is quite large, as expected for mner-shell double-hole states. The sulphur K-LL Auger energies of H$S and SO, are grven along with theoretical and experimental data of Keski-Rahkonen et al. [3] m table 2. The SCF vdues are in fair agreement with experiment while rhe POCI values are almost uniformly smaller by aboat 40 eV (which is mostly the relaxation energy). However the POCI chemical shifts in Auger enerw, AAE = AE(SO,) - AE(H2S) are m good agreement with experiment, whrle the SCF values are not. A ssimilar srtuation IS encountered for the double ionization potentials of H,S and SO,. also shown in table 2. The above results indicate that m the POCI method the results OR H?S are of similar accuracy to those of SO,, while in the SCF method the theoretical deficiencies are more pronounced for SO2 than H$%. The relative positions of the Auger lines of H$S and SO2 with respect to those of the lS lines are given in table 3. The POCI and the SCF values show the invariance m the term splittings, which is also found experimentally, between H,S and SO,. The theoretical values of the te_m splittrngs are slightly smaller than the expenmental. This is so because in our cdcdations the effect of electron correlatron is not included 121. At this stage the conclusron is that the POCI method
67
Table 1 Theoretrcal
results on the LL double-hole
st&tes of H2S
Approximate atomrc state
Leadmg electronic configurations (POW
3P
3Az
0.9996(1bl
Ibt)
(s’p’)
3B1
0.9996(1b1
3a1)
392
0.9997(3nr
lb21
‘A* *AZ
0.9995(lb,
lbz)
0.7112(ib;)
rB2
0.9996(
‘D (S2P4)
rAl ‘S (sZp4) 3P (S’P?
- ~_7019(lb~)
EC1 a1
E re,wb)
E;‘~’
(ev)
@W
(harkree)
0.16
37.55
-383.445
0.18
37.53
-383.43507
0.23
37 44
-383.44451
0.21
37.31
-383.21151
98
37.36
-383.21153
0 18
37.30
-2
lb2 3ar )
0.4149CIb~)
+ 0.4023(1bz)
lBr
0.9994(1bl
3ai)
1Al
O.S702(3&
+ 0.567S(lb;)
- O.S155(3a;)
-2
f 0.57OUlb:)
-383.21111
0.24
-383.20844
3.56
-382.97152
38.54
-381.43983
0.09
38.43
-381.43879 -381.43866
lb,)
0.31
36.08
-380.65172
Za,)
0 25
36.24
-380.65
3at)
0.27
36 18
-380.65140
3.21
36.68
-378.6919’
3BZ
0.9997t2a1
lbl)
0.12
0.9997(2a,
3al)
0. I 1
3B
0.9998(2ar
lbz)
IB, ‘B,
0.9994(2a, 0.9995(1b2
lA1
0.9994(2ar
‘4
0.9865(2at)
2
(s’p’)
‘S
-383.21130
88
3A1
‘P
19
169
tsO$,
a) EC1 = Er - H,,. Table 2 Sulphur #-LL
=
Auger energes
l-ma1 state
~~
W Ere,&,.
Ejfocl -
Es?
and LL doubltxonuatmn
Method
-
potentrais m H2S znd SOz (eV) Chemuxl
SO2
H2S
shift
IP
AE
IP
AE
AtP
&ME
3P (S2PJ,
POCI SCIexpt. a)
413.94 376.42
2062.79 2100.30
424.75
2059.31
10.81 12.2 af
-3 49 -5.0 a)
‘D
POCI SCF expt. a)
420.31 382_94 379.8
2056.43 2093.78 2098.7
431.12
2052.94
388.2
2095.5
10.81 12.6 a) 8.4
-3.48 -6.0 a) -3.2
POCI SCF eupt. a)
426.82
2049.91
437.63
2046.43
10.81 12.6 a)
388
209 1
-3.48 -6.0 a) -
3P (SIPSf
POCI SCF e\pt. a)
468 53 430.02 431.5
2008.21 2046.70 2047.0
479.33
2004.73 -
439.8
2043.9
10.8 12.6 a) 8.3
-3.79 -5.0 a) -3.1
‘P (sl P’)
POCI SCF eupt.a)
489.94
1986.78
500.77
1983.29
10.83
-3.49
453.79 452.3
2022.93 2026.2
460.7
2023.0
12.6 a) 8-4
-6.0 -3.2
POCl SCF evpt a)
543.27 506.58 508.2
1333.46 1970.14 1970.3
554.09
1929.97
516
1967.8
10.82 12.7 a) 7.8
-3.49 -5.0 a) -2.5
(sZpJ,
‘S (S’P4)
‘S
(s0p6) al From ref. [3].
a)
CHEhUCAL PHYSICS LETTERS
VoIume 69, number 1 Table 3 Relattve posItions of the K-LL Double-hole
state
1 January
1980
lines in H2S and SO? with respect to the position of the ‘S lutes (ev) W
5332
POCI
evpt a)
sff
expt a)
POCI
3P (sZp4,
129.33
130.16
-
129.34
t D (s2p4) ‘s (sZp4,
12297 116.45
123.65 -
1284 120.7
122.97 116.46
JP (51 ps) IP (sl p5) l s (sOp6)
74.75 53.32 0.00 (1933.46)
76.56 5281 0.00 (197C.i4)
76.7 55.9 0.00 (1970.3)
127-7 -
74.76 53.32 0.00 (1929.97)
76. i 55.2 0.30 (1967.8)
a) From ref. [3]. IS less sensitive
to theoretlcal defkiencres than the MC SCF and thus it should be more rehable for the cakuIatlon of AE chemical shrfts and those in double ioruzation potentsals 3 2.
ti=
The sulphur K-LL Auger energes of the model molecules and those obtamed from POCK calculations are summarized m tabIe 4. Au calculations (except for H,S) were carned out usmg a double-zeta basis [4]. The chemical shfts in the Auger lmes may be expressed in terms of the chemical shifts m single and double loruzatlon potentials.
Doublehole state
HzS 4AE
3P (s2 p” 1
-8.14
3.51
*D (s”p4)
-8.13
1s (s7p4)
-815
3.52
3P (WI
-a15
3.52
‘P
-815 -8
‘S
17
AIP
HzS02
H1 SO2 AiE
AiP
aAE
AL?
AX
8.42
-4.44
1.41
-0.70
0.00
0.00
(42200)
(2059.28)
0.00
0.00 (205292)
8.43
-4.4 1
1.40
-0.69
(128.44) 0.00 (434.97)
0.00 (2046.39)
8.43
-4.45
1.44
-Q-73
0.00
0.00 (2004.69)
835
-4.37
1-a
-0.73
(476.67) 3.52
0.00 (498.09)
0.00 (1983.26)
835
-4.37
l-43
-0.72
3.55
0.00 (551.44)
0.00 (1929.91)
830
-4.32
1.48
-0.75
3.50
(sl$1 (sop9
Auger ener@es m the model molecules and H2S ~7th respect to those of HzSO (zv) H2S0
AIP
- PIE’@+).
Depending on the relative magnitudes of the chemical shifts in the smgle and dotible IP, the chemical shifts III AE may be increasmg or decreasing with increasing (single ionization) ESCA shift. In the series of model molecules, the chemical shift m the sulphur K-LL AE IS decreasing Hnth mcreasing chemical shift in the 2s IP (fig. 1). As shown in fig. 1, the K-LL AE changes by about 2 eV per formal charge or formal oxidation number. The corresponding change between H+ and SO2 is 0.58 eV (decreasing) per formal charge, in good agreement uinth experiment (about 0.52 eV per formal charge (31). Thus it appears that the magnitude of the
Chemical shifts of H2S, H2S0, H&TO2 and H2SU2
Table 4 Sulphur LL lonlzatlon potentials and K-LL
AlP(M*)
69
Volume 69, number 1
CHEMICAL
PHYSICS
LETTERS
1 January
1980
change m K-LL AE wth formal oxidation number on sulphur depends on the actual senes of molecules considered, since the oxldatlon number corresponds to chfferent actual charge on the atom for different senes of molecules. Use of formal charge (1-e. oxldatlon state) to correlate AJZ IS preferable to usmg partial charges obtamed by population analysis and ab irutlo calculations on molecules, since the computed charge depends on the basis set used m the calculation. References
a
TIP 1. Variation of I; Iomzat1on potential (‘S). LL double ionization porentlai (‘D) and K-LL Auger energy (‘S-l D uqth formal oxidation state of sulphur m moiccules.
70
[ 11 CA. Coulson and F.A. Glanturco, J. Phys. I31 (1968) 605. 121 B.J. Lmdberg, Ii, Hamnn, G. Johansson. U. Gekus, A. Fahlman, C. Nordlmg and Z;. Slegbahn, Physica Scnpta 1 (1970) 286. I33 0. Kesh-Rahkonen and M-0. Krause, J. Election Spectry 9 (1976) 371, K. Faegrt Jr. and 0. Kesh-Rahkonen. J. Electron Spectry. 11 (1977) 275. ja] L. Asplund, P. Kelfve, H. Siegbahn. 0. Goscmsh. H. rellnerFeldeg K. Hamnn. B. Blomster and K. Siegbahn. Chcm Phys Letrers 10 (1976) 353 [S] R-H. Eade, h1.A. Robb, G. Theodorakopoulos and LG. Cszmadla, Chem Phys. Letters 52 (1977) 526. [61 X1-A. Robb, G. TheodorakopouIos and 1.G CsumadIa, Chem. Phyr Letters 57 (1978) 423. [ 7J G. Theodorakopoulos. LG. Cslzmala. MA. Robb. A. Kucsman and I. Kapowts, J. C&m. Sot. Faraday Trans. II 73 (1977) 293.
Volume 69, number 1
THEORETICAL
INVESTIGATION
1
PH\ SICS LETTERS
OF THE SULPHUR K-LL
Januarq 1980
AUGER ENERGIES
AND CHEMICAL SHIFTS IN A SERIES OF SULPHUR COMPOUNDS Gmmoula THEODORAKOPOUL9S Deparrmrrrr of Ckrn~sr~
%. Imre G CSIZhlADlA
Unlr ersrr1 of Toronto, Toronto. Canada .V_5S I 1 I
and hhchael
A ROBB
Deparrrnenr o~~Clrcrmst~~ Queer Ekaberh Recewed
College, Londolr R’S 7AH, UK
1 August 1979
Tuo scrles of rnvestrganons arc reported on LL doublehole states oi molecules contammg sulphur. rust. the results on the LL double roruzat1on potentI& an-l ii-LL Auger energies oi Hz.5 and SO2 show that the use oi a irozen-orbrtal approw matron IS preferable to SCI methods for calculation of chemrcal shlits m K-LL Auger cnergles and LL ronlzauon potcnttals SecondI! chemrcal shafts of K-LL Auger energes of a senes of model molecules HzS HISO, HJSO~ and HzS02 are correlated ulrh the tormal o\ldatlon state of sulphur. This corrclatron Ewes a shaft of 11 eV m Auger energy per iormal charge on sulphur.
1. Introduction The effect of chemical bondmg on the energes of transmons mkolvmg inner-shell electrons has been studred rather eltenslvely for X-ray fluorescence and ESCA processes and to a lesser extent for Auger processes [l-31 The chemical shifts In the K-LL Auger energy (AE) of sulphur ha\e been correlated ~qth the formal charge on the atom [ 11, with the partial charge on S. as obtamed by population analysts and ab mltlo calcularlons on molecules [3], and wrth evpenmental ESCA shifts m the sulphur 2p lomzatlon potential (IP) [4]. The general trend IS decreasmg K-LL Auger energy with increasmg L shell IP [4] and decreasmg AE v.?th increasmg formal or partial charge on sulphur [1.3]. A tift of 16 eV per formal charge was predlcted by a theoretIcal study of K-LL Auger energy In the sulphur atom and posltlve ions [ 11. lhs result IS an overestlmatlon of the AE chemical shifts smce the formal
charge or oudatlon state in molecules IS not the actual charge on the atom as It IS m the free atom The ekpenmental values obtamed for molecules are much smaller than 16 eV: the Difference in K-LL AE between the two types of sulphur m NalS203 (S’-, S6+), is 4.3 eV [l], or about 0.5 eV per?orrnal charge. In the present paper. two series of investlgatlons are reported. First, the Inner-shell double-hole states of HZS and SO? are computed usmg multlconfiguratlon SCF (MC SCF) and CI methods which were proven efficient for the assqnment of valence-shell Auger spectra of H2S and SO2 [5,6]. The results on the LL double iontzation potentials and K-LL Auger energes are compared blth expenmental data [3], to test the vahtity of the theorerlcal models used. Secondly, calculatlons on the model molecules H,SO,H,SO, and H2S02 [7] have been performed to mvestigate the chemtcal stifts in the Auger energies as a functron of the formal sulphur oxidation state. 1. Theory
l
Present address Theoreucal Chemistry NatIonal Hellemc Research Foundatron,
66
The AthensSOl/l. Greece.
institute.
The L shell double-hole
states of sulphur
m mole-
Volume 69, number 1
PHYSICS LET-l-ERS
CHELIICAL
cules may be approximately classified usrng the atomic LS terms: IS (2s02p6), lv3P (2s12p5) and 3P, lD, IS (2~~2~~). In general, on restnction to a cubic group m the mclecule, the degeneracy wrll be shghtly broken. However, the wavefunctions wrll be very close to atomrc LS ergenfunctions that have been adopted for the relevant cubic group. Thus, for example, m CZv symmetry three states of symmetry 1A, ansmg from ‘D and 1 S (s2p4), retam the appro_xunate form
(1) ID IAl
= 6-i/2
(2
‘S IAl
= 3-ii2
PZ PZ - PX PX - P_v PJ) * -
(2) (3)
For thrs reason rt IS essential to use multrconfiguration methods. In the present work we have used the MC SCF method that has been drscussed prevrous!y [5]. In addrtron we have used the parent orbital configuratron Interaction (POCI) method (correspondmg to a frozen-orbital approximatron). In tlus method the double-hole configuratrons are constructed usmg the MO of the parent molecule and the double-hole states computed by dragonahzmg the hamrltoruan matrix of the doubly posrtrve ion over the double-hole configuratrons. The POCI method for double-hole states is analogous to usmg Koopmans’ theorem for smgle-hole states of molecules and it has been shown that the POCI method is useful in assqning the suIphur L-mm’ and the oxygen K-mm’
Auger spectra of SO2 [6]. The POCI total energy of the inner-shell hole states of molecules
double-
1s lugher than the SCF total
energy of these states and the difference IS a measure of the relaxation energy of double-hole states SCF _ E;OC’ E relax = ET
The contnbutron figuratron mteractron proxrmatron may be tween the eigenvalue onal matrix element dragonahzation (H,), Ecl=E,-H,,. I
_
(4)
to the total energy due to con(EC’) at the frozen-orbital apobtamed as the drfference be(E,) and the correspondmg dragof the hamrltonian matrix before
(5)
3. Results
I January 1980
and discussion
3.1. AfC SCF and FOCI calculntiotts on H$
and SO,
PoCl and MC SCF calculations were carried out on the L shell double-hole states of H2S using a doublezeta basrs set augmented wrth floating p functions as m ref. [5] _ For SO,, calculations have been carried out only at the POCI level (the basis sets are as reported in ref. [6]). To rIlustrate the general form of the rest&s obtained in the calculations we give the MC SCF and POCE results on H2S m some detarl m table 1_ These data are typical of those obtamed for the other sulphur-containing molecules studred m thrs work. From an inspection of column 1 of table 1 (leading electronic configuratron), we confirm that the eigenfunctions FolIow the LS couphng scheme (compare lines 5,7, and 9 with the LS couphng coefflcrents in eqs. (l), (2j and (3)). The configuratron-mteraction contribution to the total energies is generally smaU (cf. EC1 column in table l), except for the IAl states m the LD and tS terms. The relaxatron energy (Erelau in table I) is quite large, as expected for mner-shell double-hole states. The sulphur K-LL Auger energies of H$S and SO, are grven along with theoretical and experimental data of Keski-Rahkonen et al. [3] m table 2. The SCF vdues are in fair agreement with experiment while rhe POCI values are almost uniformly smaller by aboat 40 eV (which is mostly the relaxation energy). However the POCI chemical shifts in Auger enerw, AAE = AE(SO,) - AE(H2S) are m good agreement with experiment, whrle the SCF values are not. A ssimilar srtuation IS encountered for the double ionization potentials of H,S and SO,. also shown in table 2. The above results indicate that m the POCI method the results OR H?S are of similar accuracy to those of SO,, while in the SCF method the theoretical deficiencies are more pronounced for SO2 than H$%. The relative positions of the Auger lines of H$S and SO2 with respect to those of the lS lines are given in table 3. The POCI and the SCF values show the invariance m the term splittings, which is also found experimentally, between H,S and SO,. The theoretical values of the te_m splittrngs are slightly smaller than the expenmental. This is so because in our cdcdations the effect of electron correlatron is not included 121. At this stage the conclusron is that the POCI method
67
Table 1 Theoretrcal
results on the LL double-hole
st&tes of H2S
Approximate atomrc state
Leadmg electronic configurations (POW
3P
3Az
0.9996(1bl
Ibt)
(s’p’)
3B1
0.9996(1b1
3a1)
392
0.9997(3nr
lb21
‘A* *AZ
0.9995(lb,
lbz)
0.7112(ib;)
rB2
0.9996(
‘D (S2P4)
rAl ‘S (sZp4) 3P (S’P?
- ~_7019(lb~)
EC1 a1
E re,wb)
E;‘~’
(ev)
@W
(harkree)
0.16
37.55
-383.445
0.18
37.53
-383.43507
0.23
37 44
-383.44451
0.21
37.31
-383.21151
98
37.36
-383.21153
0 18
37.30
-2
lb2 3ar )
0.4149CIb~)
+ 0.4023(1bz)
lBr
0.9994(1bl
3ai)
1Al
O.S702(3&
+ 0.567S(lb;)
- O.S155(3a;)
-2
f 0.57OUlb:)
-383.21111
0.24
-383.20844
3.56
-382.97152
38.54
-381.43983
0.09
38.43
-381.43879 -381.43866
lb,)
0.31
36.08
-380.65172
Za,)
0 25
36.24
-380.65
3at)
0.27
36 18
-380.65140
3.21
36.68
-378.6919’
3BZ
0.9997t2a1
lbl)
0.12
0.9997(2a,
3al)
0. I 1
3B
0.9998(2ar
lbz)
IB, ‘B,
0.9994(2a, 0.9995(1b2
lA1
0.9994(2ar
‘4
0.9865(2at)
2
(s’p’)
‘S
-383.21130
88
3A1
‘P
19
169
tsO$,
a) EC1 = Er - H,,. Table 2 Sulphur #-LL
=
Auger energes
l-ma1 state
~~
W Ere,&,.
Ejfocl -
Es?
and LL doubltxonuatmn
Method
-
potentrais m H2S znd SOz (eV) Chemuxl
SO2
H2S
shift
IP
AE
IP
AE
AtP
&ME
3P (S2PJ,
POCI SCIexpt. a)
413.94 376.42
2062.79 2100.30
424.75
2059.31
10.81 12.2 af
-3 49 -5.0 a)
‘D
POCI SCF expt. a)
420.31 382_94 379.8
2056.43 2093.78 2098.7
431.12
2052.94
388.2
2095.5
10.81 12.6 a) 8.4
-3.48 -6.0 a) -3.2
POCI SCF eupt. a)
426.82
2049.91
437.63
2046.43
10.81 12.6 a)
388
209 1
-3.48 -6.0 a) -
3P (SIPSf
POCI SCF e\pt. a)
468 53 430.02 431.5
2008.21 2046.70 2047.0
479.33
2004.73 -
439.8
2043.9
10.8 12.6 a) 8.3
-3.79 -5.0 a) -3.1
‘P (sl P’)
POCI SCF eupt.a)
489.94
1986.78
500.77
1983.29
10.83
-3.49
453.79 452.3
2022.93 2026.2
460.7
2023.0
12.6 a) 8-4
-6.0 -3.2
POCl SCF evpt a)
543.27 506.58 508.2
1333.46 1970.14 1970.3
554.09
1929.97
516
1967.8
10.82 12.7 a) 7.8
-3.49 -5.0 a) -2.5
(sZpJ,
‘S (S’P4)
‘S
(s0p6) al From ref. [3].
a)
CHEhUCAL PHYSICS LETTERS
VoIume 69, number 1 Table 3 Relattve posItions of the K-LL Double-hole
state
1 January
1980
lines in H2S and SO? with respect to the position of the ‘S lutes (ev) W
5332
POCI
evpt a)
sff
expt a)
POCI
3P (sZp4,
129.33
130.16
-
129.34
t D (s2p4) ‘s (sZp4,
12297 116.45
123.65 -
1284 120.7
122.97 116.46
JP (51 ps) IP (sl p5) l s (sOp6)
74.75 53.32 0.00 (1933.46)
76.56 5281 0.00 (197C.i4)
76.7 55.9 0.00 (1970.3)
127-7 -
74.76 53.32 0.00 (1929.97)
76. i 55.2 0.30 (1967.8)
a) From ref. [3]. IS less sensitive
to theoretlcal defkiencres than the MC SCF and thus it should be more rehable for the cakuIatlon of AE chemical shrfts and those in double ioruzation potentsals 3 2.
ti=
The sulphur K-LL Auger energes of the model molecules and those obtamed from POCK calculations are summarized m tabIe 4. Au calculations (except for H,S) were carned out usmg a double-zeta basis [4]. The chemical shfts in the Auger lmes may be expressed in terms of the chemical shifts m single and double loruzatlon potentials.
Doublehole state
HzS 4AE
3P (s2 p” 1
-8.14
3.51
*D (s”p4)
-8.13
1s (s7p4)
-815
3.52
3P (WI
-a15
3.52
‘P
-815 -8
‘S
17
AIP
HzS02
H1 SO2 AiE
AiP
aAE
AL?
AX
8.42
-4.44
1.41
-0.70
0.00
0.00
(42200)
(2059.28)
0.00
0.00 (205292)
8.43
-4.4 1
1.40
-0.69
(128.44) 0.00 (434.97)
0.00 (2046.39)
8.43
-4.45
1.44
-Q-73
0.00
0.00 (2004.69)
835
-4.37
1-a
-0.73
(476.67) 3.52
0.00 (498.09)
0.00 (1983.26)
835
-4.37
l-43
-0.72
3.55
0.00 (551.44)
0.00 (1929.91)
830
-4.32
1.48
-0.75
3.50
(sl$1 (sop9
Auger ener@es m the model molecules and H2S ~7th respect to those of HzSO (zv) H2S0
AIP
- PIE’@+).
Depending on the relative magnitudes of the chemical shifts in the smgle and dotible IP, the chemical shifts III AE may be increasmg or decreasing with increasing (single ionization) ESCA shift. In the series of model molecules, the chemical shift m the sulphur K-LL AE IS decreasing Hnth mcreasing chemical shift in the 2s IP (fig. 1). As shown in fig. 1, the K-LL AE changes by about 2 eV per formal charge or formal oxidation number. The corresponding change between H+ and SO2 is 0.58 eV (decreasing) per formal charge, in good agreement uinth experiment (about 0.52 eV per formal charge (31). Thus it appears that the magnitude of the
Chemical shifts of H2S, H2S0, H&TO2 and H2SU2
Table 4 Sulphur LL lonlzatlon potentials and K-LL
AlP(M*)
69
Volume 69, number 1
CHEMICAL
PHYSICS
LETTERS
1 January
1980
change m K-LL AE wth formal oxidation number on sulphur depends on the actual senes of molecules considered, since the oxldatlon number corresponds to chfferent actual charge on the atom for different senes of molecules. Use of formal charge (1-e. oxldatlon state) to correlate AJZ IS preferable to usmg partial charges obtamed by population analysis and ab irutlo calculations on molecules, since the computed charge depends on the basis set used m the calculation. References
a
TIP 1. Variation of I; Iomzat1on potential (‘S). LL double ionization porentlai (‘D) and K-LL Auger energy (‘S-l D uqth formal oxidation state of sulphur m moiccules.
70
[ 11 CA. Coulson and F.A. Glanturco, J. Phys. I31 (1968) 605. 121 B.J. Lmdberg, Ii, Hamnn, G. Johansson. U. Gekus, A. Fahlman, C. Nordlmg and Z;. Slegbahn, Physica Scnpta 1 (1970) 286. I33 0. Kesh-Rahkonen and M-0. Krause, J. Election Spectry 9 (1976) 371, K. Faegrt Jr. and 0. Kesh-Rahkonen. J. Electron Spectry. 11 (1977) 275. ja] L. Asplund, P. Kelfve, H. Siegbahn. 0. Goscmsh. H. rellnerFeldeg K. Hamnn. B. Blomster and K. Siegbahn. Chcm Phys Letrers 10 (1976) 353 [S] R-H. Eade, h1.A. Robb, G. Theodorakopoulos and LG. Cszmadla, Chem Phys. Letters 52 (1977) 526. [61 X1-A. Robb, G. TheodorakopouIos and 1.G CsumadIa, Chem. Phyr Letters 57 (1978) 423. [ 7J G. Theodorakopoulos. LG. Cslzmala. MA. Robb. A. Kucsman and I. Kapowts, J. C&m. Sot. Faraday Trans. II 73 (1977) 293.