Photodissociative excitation processes of XeF2 in the vacuum ultraviolet region 105–180 nm

Abstract

Photodissociative excitation processes of XeF 2 are studied by absorption and photofragment fluorescence spectroscopies in the vacuum UV region 105-180 nm. The quantum yields are measured along with the dispersed fluorescence spectra for emissions from XeF* ͑B, C, and D͒ excimers formed from XeF 2 excited by linearly polarized, monochromatized synchrotron radiation. Fluorescence anisotropy, R, of XeF* fragment emission was also measured against excitation light wavelength in the region 105-165 nm. The quantum yields for XeF* excimer formation are found to be very high; especially in the valence band region shorter than 130 nm it reaches almost unity. From the fluorescence measurements we have observed new peaks assigned to 5 u →5dR Rydberg transitions. The intense 5 u3/2 →6sR bands which appear around 143 nm exhibit no fluorescence excitation bands; even fluorescence dips are observed at 143.18 and 144.25 nm whereas very weak positive fluorescence bands are observed at 141.04 and 142.11 nm. The R values for the very broad valence bands which underlie intense Rydberg bands are found to be high. The 5 u series of Rydberg bands exhibit low R values. Based on the energetics and the results of quantum yields and fluorescence anisotropy values, the valence and Rydberg bands observed are assigned from the viewpoint of symmetry of the excited state, and the dynamics of the dissociation processes is discussed.

Microstructuring of Si(100) by light induced dry etching in the VUV

“…The absorption spectrum of XeF 2 consists of a broad maximum around 158 nm due to valence excitations and several progressions of sharp Rydberg transitions at shorter wavelengths. XeF 2 dissociates in this spectral range with high efficiency to XeF and F [8][9][10]. Fragments from the dissociation, reach by diffusion, according to the large mean free path, parts below the mask and cause the unselective etching.…”

Multiterawatt Hybrid (Solid/Gas) Femtosecond Systems in the Visible

“…Behind the optical pumping XeF active medium is the photolysis of XeF 2 vapor in the spectral range of <204 nm to produce XeF excimers mainly in the B state [17][18][19]. The C state, lying lower than the B state, is populated due to collisional relaxation of the latter in the presence of a buffer gas.…”

Photodissociation spectroscopy of ClCN in the vacuum ultraviolet region

“…The details in the PEM±MCS technique have been described in Ref. [11]. The statistical errors in the measurement of the I k aI c ratio gave rise to the uncertainty of $0.01 of R.…”

“…The experimental apparatus and procedures employed in the present study have been described in the previous paper [8,9,11]. The measurement was performed at the BL2A stage of UVSOR in the Institute for Molecular Science.…”