Cross section measurements for photodetachment or photodissociation of ions produced in gaseous mixtures of O2, CO2, and H2O

Abstract

A drift tube mass spectrometer coupled with a continuous laser photon source has been used to study photodissociation of thermal energy positive ion clusters. Absolute photodissociation cross sections have been measured for O2 +(H2O)1,2, O2 +(O2), O2 +(CO2), and H+(H2O)n=1–4 at room temperature and for low field conditions (10 or 14.3×10−21 V m2). Photon wavelengths ranging from 676.4 to 454.5 nm were studied. The H+(H2O)n=1–4 were found to have small or zero cross sections; upper limits on their cross sections were obtained. The O2 +(H2O) and O2+(CO2) cross sections behave similarly over part of the photon energy range. Near 2.60 eV both ions have cross sections approaching 6×10−22 m2. The photodissociation of O2 +(CO2) produces a CO2 + photofragment. From the appearance of this fragment an upper bound on the dissociation energy of O2 +(CO2) was placed at 0.46 eV.

Photochemistry of Ions at D-region Altitudes of the Ionosphere: A Review

“…The calculations based on this photodetachment cross section of Cl -result in K 1 det (Cl -) = 0.064 s -1 . The measured photodetachment cross section of O 2 -given by Lee and Smith (1979) at wavelengths between 350 and 840 nm agrees with the data presented by Beyer and Vanderhoff (1976) and Cosby et al (1976) in the photon energy range from 1.8 to 2.7 eV (459 B k B 689 nm). It is necessary to take into account the photodetachment cross section of O 2 -measured by Hodges et al (1980) at 248.4 and 351.1 nm wavelengths.…”

Photofragmentation of mass-selected ICl−(CO2)n cluster ions: Solvation effects on the structure and dynamics of the ionic chromophore

“…Moreover, photon-assisted charge transfer reactions are often observed in cationic clusters. [36][37][38] Shen and Farrar 38 have studied the size-dependent effects in the photodissociation spectra of Sr ϩ ͑NH 3 ͒ n and have proposed an intramolecular electron transfer mechanism to account for the observed spectral features. These charge transfer to solvent ͑or vice versa͒ transitions are also common in solution.…”

Vibronic coupling in the superoxide anion: The vibrational dependence of the photoelectron angular distribution

“…A comparison of O 2 − photodetachment results with atomic anion model predictions yields considerable insight into the effect of vibrational excitation on the photodetachment properties, in particular the PAD. 1 Several detachment studies of this species have probed the photon energy dependence of the total detachment cross section [19][20][21][22][23][24][25][26] or reported the photoelectron spectrum of O 2 − . 1,[27][28][29][30][31][32][33][34][35][36][37][38] Until very recently, much less data were reported regarding the PAD.…”