Photodissociation of vibrationally excited Ar2+ formed by associative ionization
| Autor: | J. A. Welsh, J. F. Paulson, T. L. Rose, D. H. Katayama |
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| Rok vydání: | 1979 |
| Předmět: | |
| Zdroj: | The Journal of Chemical Physics. 70:4542-4551 |
| ISSN: | 1089-7690 0021-9606 |
| Popis: | The photodissociation cross sections of a beam of Ar2+ formed by associative ionization in a conventional electron impact ion source have been measured over the wavelength range from 265 to 715 nm. The measured cross sections are for transitions from the 2Σu+ ground state to the repulsive 2Σg+ excited state and are dependent on the ion source conditions. At low pressures (0.01 Torr) in the ion source, the cross section is 1×10−17 cm2 and varies little over the entire wavelength range. When pressures are increased to 0.1 Torr, a peak in the cross section at about 300 nm is obtained with a value of 1.7×10−17 cm2. A simplified two state mechanism involving high and low lying vibrational levels of Ar2+ in its ground state is proposed to explain the qualitative effects of pressure on the cross sections. Measurement of the Ar2+ and Ar+ beam currents as a function of repeller voltage showed that collisional dissociation is occurring in the ion source under conditions of relatively high pressure and positive repe... |
| Databáze: | OpenAIRE |
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