Vacuum-UV negative photoion spectroscopy of SF5CF3

• Published in: The Journal of chemical physics Vol. 128; no. 12; p. 124315
• Main Authors: Simpson, M J, Tuckett, R P, Dunn, K F, Hunniford, C A, Latimer, C J, Scully, S W J
• Format: Journal Article
• Language: English
• Published: United States 28.03.2008
• ISSN: 0021-9606
• DOI: 10.1063/1.2894869

Ion pair formation, generically described as AB-->A(+)+B(-), from vacuum-UV photoexcitation of trifluoromethyl sulfur pentafluoride, SF(5)CF(3), has been studied by anion mass spectrometry using synchrotron radiation in the photon energy range of 10-35 eV. The anions F(-), F(2)(-), and SF(x)(-) (x=1-5) are observed. With the exception of SF(5)(-), the anions observed show a linear dependence of signal with pressure, showing that they arise from ion pair formation. SF(5)(-) arises from dissociative electron attachment, following photoionization of SF(5)CF(3) as the source of low-energy electrons. Cross sections for anion production are put on to an absolute scale by calibration of the signal strengths with those of F(-) from both SF(6) and CF(4). Quantum yields for anion production from SF(5)CF(3), spanning the range of 10(-7)-10(-4), are obtained using vacuum-UV absorption cross sections. Unlike SF(6) and CF(4), the quantum yield for F(-) production from SF(5)CF(3) increases above the onset of photoionization.