Abstract
Photon-exposure-dependent positive- and negative-ion photon-stimulated desorption (PSD) was proposed to study the photoreactions and obtain the photolysis cross sections of molecules adsorbed on a single-crystal surface by monochromatic soft x-ray photons with energy near the core level of adsorbate. The changes in the F+ and F- PSD ion yields were measured from CF3Cl molecules adsorbed on Si (111) -7×7 at 30 K (CF 3Cl dose=0.3× 1015 molecules cm2, ∼0.75 monolayer) during irradiation of monochromatic soft x-ray photons near the F (1s) edge. The PSD ion yield data show the following characteristics: (a) The dissociation of adsorbed CF3Cl molecules is due to a combination of direct photodissociation via excitation of F (1s) core level and substrate-mediated dissociation [dissociative attachment and dipolar dissociation induced by the photoelectrons emitting from the silicon substrate]. (b) the F+ ion desorption is associated with the bond breaking of the surface CF3Cl, C F2 Cl, CFCl, and SiF species. (c) the F- yield is mainly due to DA and DD of the adsorbed CF3Cl molecules. (d) The surface SiF is formed by reaction of the surface Si atom with the neutral fluorine atom, F+, or F- ion produced by scission of C-F bond of CF3Cl, C F2 Cl, or CFCl species. A kinetic model was proposed for the explanation of the photolysis of this submonolayer CF3Cl -covered surface. Based on this model and the variation rates of the F+ F- signals during fixed-energy monochromatic photon bombardment at 690.2 and 692.6 eV [near the F (1s) edge], the photolysis cross section was deduced as a function of energy.
| Original language | English |
|---|---|
| Article number | 214104 |
| Journal | Journal of Chemical Physics |
| Volume | 129 |
| Issue number | 21 |
| DOIs | |
| Publication status | Published - 2008 Dec 12 |
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All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry
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Photon-exposure-dependent photon-stimulated desorption for obtaining photolysis cross section of molecules adsorbed on surface by monochromatic soft x-ray photons. / Chou, L. C.; Jang, C. Y.; Wu, Y. H.; Tsai, W. C.; Wang, S. K.; Chen, J.; Chang, S. C.; Liu, C. C.; Shai, Y.; Wen, C. R.
In: Journal of Chemical Physics, Vol. 129, No. 21, 214104, 12.12.2008.Research output: Contribution to journal › Article
TY - JOUR
T1 - Photon-exposure-dependent photon-stimulated desorption for obtaining photolysis cross section of molecules adsorbed on surface by monochromatic soft x-ray photons
AU - Chou, L. C.
AU - Jang, C. Y.
AU - Wu, Y. H.
AU - Tsai, W. C.
AU - Wang, S. K.
AU - Chen, J.
AU - Chang, S. C.
AU - Liu, C. C.
AU - Shai, Y.
AU - Wen, C. R.
PY - 2008/12/12
Y1 - 2008/12/12
N2 - Photon-exposure-dependent positive- and negative-ion photon-stimulated desorption (PSD) was proposed to study the photoreactions and obtain the photolysis cross sections of molecules adsorbed on a single-crystal surface by monochromatic soft x-ray photons with energy near the core level of adsorbate. The changes in the F+ and F- PSD ion yields were measured from CF3Cl molecules adsorbed on Si (111) -7×7 at 30 K (CF 3Cl dose=0.3× 1015 molecules cm2, ∼0.75 monolayer) during irradiation of monochromatic soft x-ray photons near the F (1s) edge. The PSD ion yield data show the following characteristics: (a) The dissociation of adsorbed CF3Cl molecules is due to a combination of direct photodissociation via excitation of F (1s) core level and substrate-mediated dissociation [dissociative attachment and dipolar dissociation induced by the photoelectrons emitting from the silicon substrate]. (b) the F+ ion desorption is associated with the bond breaking of the surface CF3Cl, C F2 Cl, CFCl, and SiF species. (c) the F- yield is mainly due to DA and DD of the adsorbed CF3Cl molecules. (d) The surface SiF is formed by reaction of the surface Si atom with the neutral fluorine atom, F+, or F- ion produced by scission of C-F bond of CF3Cl, C F2 Cl, or CFCl species. A kinetic model was proposed for the explanation of the photolysis of this submonolayer CF3Cl -covered surface. Based on this model and the variation rates of the F+ F- signals during fixed-energy monochromatic photon bombardment at 690.2 and 692.6 eV [near the F (1s) edge], the photolysis cross section was deduced as a function of energy.
AB - Photon-exposure-dependent positive- and negative-ion photon-stimulated desorption (PSD) was proposed to study the photoreactions and obtain the photolysis cross sections of molecules adsorbed on a single-crystal surface by monochromatic soft x-ray photons with energy near the core level of adsorbate. The changes in the F+ and F- PSD ion yields were measured from CF3Cl molecules adsorbed on Si (111) -7×7 at 30 K (CF 3Cl dose=0.3× 1015 molecules cm2, ∼0.75 monolayer) during irradiation of monochromatic soft x-ray photons near the F (1s) edge. The PSD ion yield data show the following characteristics: (a) The dissociation of adsorbed CF3Cl molecules is due to a combination of direct photodissociation via excitation of F (1s) core level and substrate-mediated dissociation [dissociative attachment and dipolar dissociation induced by the photoelectrons emitting from the silicon substrate]. (b) the F+ ion desorption is associated with the bond breaking of the surface CF3Cl, C F2 Cl, CFCl, and SiF species. (c) the F- yield is mainly due to DA and DD of the adsorbed CF3Cl molecules. (d) The surface SiF is formed by reaction of the surface Si atom with the neutral fluorine atom, F+, or F- ion produced by scission of C-F bond of CF3Cl, C F2 Cl, or CFCl species. A kinetic model was proposed for the explanation of the photolysis of this submonolayer CF3Cl -covered surface. Based on this model and the variation rates of the F+ F- signals during fixed-energy monochromatic photon bombardment at 690.2 and 692.6 eV [near the F (1s) edge], the photolysis cross section was deduced as a function of energy.
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U2 - 10.1063/1.3026598
DO - 10.1063/1.3026598
M3 - Article
C2 - 19063541
AN - SCOPUS:57349179572
VL - 129
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
SN - 0021-9606
IS - 21
M1 - 214104
ER -