THE STRUCTURAL DEPENDANCE OF HF VIBRATIONAL RED SHIFTS IN ArnHFAr_{n}HF CLUSTERS VIA HIGH RESOLUTION INFRARED SPECTROSCOPY

Author Institution: Joint Institute for Laboratory Astrophysics, University of Colorado, and National Institute of Standards and Technology, and the Department of Chemistry and Biochemistry, University of ColoradoThe rotationally resolved HF stretching spectra of $Ar_{n}F. n-1-4$, have been observed using a slit jet, difference frequency infrared laser spectrometer. The red shift of the HF vibrational frequency is shown to be sensitively dependent on the placement of the Ar with respect to the HF dipole moment: the largest incremental red shift is observed for the linear ArHF. The n-1-3 red shifts rapidly approach the values observed in an Ar matrix suggesting that only the nearest neighbors contribute significantly to the perturbation of the HF vibrational frequency. The observed $Ar_{4}HF$ isomer places the fourth Ar in what would be the second layer from the HF and has little effect on the observed red shift. This supports the importance of the nearest neighbors in determining the HF vibrational frequency. In all spectra, no evidence for vibrational predissociation is observed, indicating an extremely long lived HF vibration within the cluste

HIGH RESOLUTION INFRARED SPECTRUM OF (HCl)2 - HCI STRETCH FUNDAMENTAL AND COMBINATION BAND ANALYSIS

Author Institution: Joint Institute for Laboratory Astrophysics, University of Colorado, and National Institute of Standards and Technology, and the Department of Chemistry and Biochemistry, University of ColoradoThe infrared spectrum of jet cooled $(HCl)_{3}$ has been obtained with a high resolution difference frequency infrared spectrometer. Transitions originating from each of the tunneling sublevels with excitation of both the $\nu_{1}$ (free HCl) and $\nu_{2}$ (bound HCl) for all three isotopic species have been observed. In addition, combination band transitions involving high frequency HCl stretch plus low frequency van der Waals vibrations have been observed. These transitions probe higher levels of the geared tunneling coordinate and help elucidate the details of the intermolecular potential energy surface for $HCl(v-1) + HCl(v-O)$ collisions

Physico-chemical properties of γ-irradiated International Simple Glass (ISG) nuclear waste simulants with low levels of iron impurities

The effect of γ-irradiation on physico-chemical properties of International Simple Glass (ISG) nuclear waste glass simulants with low iron impurities was investigated. The study was performed on glasses produced by Corning Inc. (named ISG-1, ISG-2) following a 0.95 MGy dose. Fourier-transform infrared and Raman spectroscopy, chemical durability tests, dilatometry, differential scanning calorimetry, electron paramagnetic resonance (EPR), optical absorption, and photoluminescence (PL) spectroscopy appraisals were done in comparison with pristine glasses. The data indicated that structural, chemical, and thermal properties were not significantly altered following γ-ray exposure. EPR spectroscopy showed radiogenic signatures from spin defects for the γ-irradiated glasses which were absent in the pristine. Optical absorption also changed significantly for the γ-irradiated glasses which exhibited defects-related features around 3.45 and 2.25 eV. The optical band gap and Urbach energies were then determined and compared with those obtained for the γ-irradiated original ISG produced by Mo-SCI Corporation. PL spectroscopy revealed distinct changes after irradiation showing enhanced high-energy emission, contrasting with the γ-irradiated original ISG. The effects of thermal treatment on optical properties of γ-irradiated glasses were finally evaluated. Potential causes at the origin of the contrasting results are discussed based on the effects of different impurities