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Pulsed nozzle Fourier transform microwave spectroscopic and ab initio investigations on the weakly bound $Ar-(H_2S)_2$ trimer

Mandal, Pankaj K and Goswami, Mausami and Arunan, E (2005) Pulsed nozzle Fourier transform microwave spectroscopic and ab initio investigations on the weakly bound $Ar-(H_2S)_2$ trimer. In: Journal of Indian Institute of Science, 85 (6). pp. 353-365.

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A pulsed nozzle Fourier transform microwave spectrometer has been used to obtain the rotational spectra of $Ar-(H_2S)_2$ and $Ar-(D_2S)_2$ trimers. Two states have been observed for each trimer and these are likely to arise due to tunneling/internal rotation of the two H2S monomers within the trimer. The rotational constants for the lower state of $Ar-(H_2S)_2$ are: A = 1810.410(6) MHz; B = 1596.199(9) MHz and C = 848.814(2) MHz; and those for $Ar-(D_2S)_2$ are A = 1725.49(1) MHz; B = 1566.26(2) MHz; and C = 826.818(3) MHz. From these rotational constants, the $Ar-H_2S$ and $H_2S-H_2S$ distances have been estimated to be 4.04 and 4.08 \AA, respectively. The splitting observed between the two states is of the order of a few MHz for $Ar-(H_2S)_2$ and a few kHz for $Ar-(D_2S)_2$. Ab initio alculations at MP2 level with large basis sets up to aug-cc-PVQZ level lead to three different minima, including a pseudo-linear one. Experimental rotational constants are consistent with the other two T-shaped structures in which Ar approaches the $(H_2S)_2$ along either its B or C axis. Single-point calculations at CCSD(T)/aug-cc-pVTZ level identifies the global minimum as having Ar along the B/C axis of $(H_2S)_2$ and it has a stabilization energy of $1.0\hspace{2mm} kcal\hspace{2mm} mol^{-1}$, after zero-point and counter-poise corrections.

Item Type: Journal Article
Publication: Journal of Indian Institute of Science
Publisher: Indian Institute of Science
Additional Information: Copyright of this article belongs to Indian Institute of Science.
Keywords: Weakly bound complexes;Intermolecular interactions;Spectroscopic methods
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 22 Oct 2007
Last Modified: 19 Sep 2010 04:40
URI: http://eprints.iisc.ac.in/id/eprint/12322

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