Determination of metastable atomic ion beam fractions by TES

Abstract

Translational energy spectroscopy (TES) has been used to measure the relative populations of several of the long-lived excited states of six atomic (C+, N+, O+, Cl+, F+ and B+) ion beams formed by electron impact ionization using 70 eV electrons. The method used is based on the excitation/de-excitation method originally devised by Moore and is discussed in detail with particular reference to the choice of O2 and NO as collision gases on spin-conservation grounds. The relative metastable populations of C+, N+, O+ and B+ reported in this paper are similar to other reports found in the literature. However, there are known reports of any measurements of the fractional abundances of the metastable states in Cl+ and F+ ion beams formed from BCl3 and CHF3 precursors respectively.

Experimental photoionization cross-section measurements in the ground and metastable state threshold region of Se+

“…Therefore, the reported cross-section measurements correspond to an unknown admixture of metastable and ground state fractions. In the case of O + [31] the metastable fractions were determined using the beam attenuation method ( 4 S 43%, 2 D 42% and 2 P 15%), clearly differing from the statistically-weighted values ( 4 S 20%, 2 D 50% and 2 P 30%) but not as much as those reported using translational energy spectroscopy ( 4 S 60%, 2 D 19% and 2 P 21%) [34]. Similarly, we do not expect statistically-weighted metastable fractions in our Se + measurements.…”

G2 ab Initio Calculations on the F+ + OH2 Singlet and Triplet Potential Energy Surfaces

“…This result may bear some relevance to the experimental observation of spin-forbidden transitions in collisions between F+ and different neutrals. 27 In this respect, it should be mentioned that this result is not found at the Hartree-Fock level of theory which predicts, on the contrary, a greater stability of the triplet global minimum 1(T). This confirms that the inclusion of electron correlation effects is unavoidable when a proper description of open-shell cations is required.…”

“…Since in many of the experimental setups the ion beams contain not only the ground state cation but also one or two of the metastable states (lD and 1S), 27 we have included in this paper a similar study of the singlet PES.…”

Thermochemistry of the Reactions F+(3P, 1D) + PH3 in the Gas Phase

“…Although the 1 D state of F + must be considered as a metastable state, it is conveniently produced in electron-impact ionization processes and subsequently detected by collision with different neutrals by means of translational-energy spectroscopy. 9 Nevertheless, to the best of our knowledge there is a complete lack of information regarding reactions between F + and PH 3 . Hence, one of the products of both the F + ( 3 P) + PH 3 and the F + ( 1 D) + PH 3 reactions.…”