10min:

AISWARYA LAKSHMI P. AND E. ARUNAN, Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India.

Recently, Raghavendra and Arunan [1] have shown that methane can form a hydrogen bonded complex with HX (X=F, Cl, OH, SH), in which H-X points towards the carbon of methane. Microwave spectroscopy has confirmed the structure of CH₄ - HF/HCl/H₂O complexes. No experimental data is available for CH₄ - H₂S complex to the best of our knowledge. Pulsed Nozzle Fourier Transform Microwave Spectrometer has been used to study the rotational spectrum of CH₄ - H₂S complex. Two progressions were observed. Both could be fitted independently to a linear top. The ground state rotational constant is determined to be B= 2683.100(1) MHz and the distortion constant to be D_J = 0.09413(9) MHz. Based on this rotational constant, the intermolecular separation is determined to be 4.136 \mathringA. The other state has a rotational constant B =2593.05(1) MHz and a negative distortion constant, D_J = -0.0089(7) MHz. The negative distortion constant implies rotational - vibrational coupling and the progression arises from some excited internal rotor/torsional state. Experiments are in progress to look for more states and isotopologues of this complex. Details will be presented in the talk.

\bigskip 1.Raghavendra et al. Chem. Phys. Lett. 467(2008)37.