Pulsed nozzle Fourier transform microwave spectrometer: Ideal to define hydrogen bond radius

Arunan, E and Tiwari, AP and Mandal, PK and Mathias, PC (2002) Pulsed nozzle Fourier transform microwave spectrometer: Ideal to define hydrogen bond radius. In: Current Science, 82 (5). pp. 533-540.

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Abstract

A pulsed nozzle Fourier transform microwave (PNFTMW) spectrometer has been recently fabricated at the Indian Institute of Science. The basic design is the same as that of Balle and Flygare. However, recent advances in microwave and computer technologies have helped in designing a state-of-theart PNFTMW spectrometer. The range of the pectrometer is from 2 to 26.5 GHz. Strong signals from OCS and several of its low abundant isotopes as well as weakly bound complexes such as $Ar-(H_2O)$, $Ar-H_2S$ and $Ar_3-H_2S$ have been obtained. For the OCS parent isotopomer, the observed line width is only 2.8 kHz, indicating the high resolution of the spectrometer. Small hyperfine splittings could also be observed from the $^{13}C$ spin-rotation interaction (4.9 kHz) in OCS and the I = 1 state of $H_2O$ (10 kHz) in $Ar-H_2O$ complex. This article gives the details of the newly fabricated PNFTMW spectrometer. By analysing the structural data available in the literature, most of it using PNFTMW spectrometer, we had recently defined a ‘hydrogen bond radius’ for all the hydrogen halides. This approach is extended to acetylene and water in this article, as models for the OH and CH groups involved in H bonding in biological systems. The H bond radius for H2O is 0.78 ± 0.07 Å and that of $C_2H_2$ is 1.09 ± 0.05 Å.

Item Type:	Journal Article
Publication:	Current Science
Publisher:	Indian Academy of Sciences
Additional Information:	Copyright of this article belongs to Indian Academy of Sciences.
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	09 Jun 2006
Last Modified:	19 Sep 2010 04:29
URI:	http://eprints.iisc.ac.in/id/eprint/7567

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