On microwave discharge sources of new chemical species for matrix-isolation spectroscopy and the identification of charged species

Abstract

Articles you may be interested inIntense, hyperthermal source of organic radicals for matrix-isolation spectroscopy Rev. Sci. Instrum. 74, 3077 (2003); 10.1063/1.1574397Luminescence spectroscopy of matrix-isolated atomic cadmium J. Chem. Phys. 110, 3903 (1999); 10.1063/1.478244 ESR and optical spectroscopy of matrixisolated ethylnitreneThe mechanism for trapping new chemical species by condensing the products of a microwave discharge with inert matrices has been investigated. Variation of geometrical, electrical, and chemical parameters of the Ar, HCI, CI 2 system indicated that the major product species-HCl2 radical or anion-was formed under conditions where neither ions nor atomic species produced in the discharge were condensed in the matrix. The mechanism for forming the product species is vacuum ultraviolet photolysis of the sample during deposition with radiation from the microwave discharge, since a coaxial orifice discharge tube provided photolysis and produced the product species, while studies with an off-axis orifice discharge tube, which could not serve as a photolysis source, did not produce the product. The H atom-Cl 2 reaction gave HCI using both discharge tubes, but the HCl l species was produced only with the coaxial tube. Hence, this species requires vacuum ultraviolet light in addition to Hand CI atoms for its production, and its identification as HCI, is strongly supported. Similar observations of ArnD+ and 0 3 with the coaxial tube, but not with the off-axis tube, confirm their identification as charged species.

Neutralization of solvated protons and formation of noble-gas hydride molecules: Matrix-isolation indications of tunneling mechanisms?

“…[2][3][4] These cations can also be trapped in noble-gas matrices upon direct deposition of hydrogen through discharge, as it was done in the pioneering works on these species. [5][6][7] An intriguing question concerns the experimentally observed decay of the cations at low temperatures, which is not fully understood to date. For example, it was suggested that room-temperature background radiation could accelerate the diffusion of protons and deuterons in the matrix and explain the faster decay of protons.…”

Neutral rare-gas containing charge-transfer molecules in solid matrices. I. HXeCl, HXeBr, HXeI, and HKrCl in Kr and Xe

“…The structure of all these species is linear centrosymmetric. 5,6,8,9,[37][38][39][40][41][42] Annealing of the extensively irradiated solids near 40 K causes the appearance of strong IR-absorptions in the 800- Annealing the photolyzed matrix at 45 K yields the uppermost spectrum with basically two extremely intense bands. It is to be noted that all of the spectra shown are drawn in the same absorbance scale.…”

Diffusion of hydrogen in rare gas solids: neutral H atoms and H+ protons

“…At first, an assignment to a neutral H atom trapped in an interstitial site in the rare-gas solid was preferred, since it was not understood how ions could be produced under the conditions of some of the experiments. Later studies, however, have shown rather conclusively that the absorptions are, in fact, due to the positively charged protons, 14,15 which form strongly bound, linear centrosymmetric RgH ϩ Rg cations in the matrix. These are characterized by a very intense asymmetric stretching infrared absorption 3 , accompanied by a progression of 3 ϩn 1 combination bands.…”

“…Particularly interesting is the mobility of the lightest and most abundant atom of them all-the hydrogen atom. Atomic hydrogen can, in fact, exist in the host at least in two varieties-as neutral atoms 4-12 and as charged protons, [13][14][15][16][17][18] and both of them have been studied in-depth spectroscopically.…”