Molecular spectroscopy is the most powerful method to study properties and dynamics of molecules. We carry out a wide range of experiments throughout the entire electromagnetic spectrum. Studies of van der Waals molecules formed in supersonic beam expansions provide great insight into intermolecular interactions. The upper left panel in the figure shows a portion of the ratio frequency spectrum of acetylene dimer. Experimental results are combined with theoretical calculations to generate accurate intermolecular potential surfaces, with one example for (HCCH)2 shown in the lower left panel of the figure.
The two panels in the center of the figure relate to a series of experiments designed to study properties of highly excited vibrational states of molecules. The top center panel is a schematic diagram of a laser-microwave double resonance spectrometer. An infrared or visible laser is used to excite molecules into a high energy state. While the molecules are in these normally inaccessible energy levels, a second transition in the radio frequency or microwave portion of the spectrum is observed. The bottom center portion of the figure shows a microwave transition in ammonia obtained in an excited N-H stretching state. These transitions are observed in an electric field, to measure electric dipole moments in excited vibrational states.
The right most portion of the figure moves to the ultraviolet portion of the spectrum, and these two sketches describe an experiment used to measure dipole moments in excited electronic states. The upper right panel outlines a Stark quantum beat spectrometer. A frequency doubled pulsed dye laser electronically excites a molecular beam. The Stark effect splits up the energy levels and the laser excites a coherent superposition of these "Stark components". The lower right panel shows fluorescence from SO2 exhibiting Stark quantum beats that come from this coherent excitation.
Prozument, K., Park, G.B., Shaver, R.G., Vasiliou, A.K., Oldham, J.M., David, D.E., Muenter, J. S., Stanton, J.F., Suits, A.G., Ellison, G.B., Field, R.W. "Chirped Pulse Millimeter Wave Spectroscopy for Dynamics and Kinetics Studies of Pyrolysis Reactions," Phys. Chem. Chem. Phys. 2014, 16, 15739.
Prozument, K., Shaver, R.G., Ciuba, M., Muenter, J. S., Park, B., Stanton, J., Guo, H., Wang, B.M., Perry, D.S., Field, R.W. "A New Approach to Transition State Spectroscopy," Faraday Discussions 2013, 163, 33.
Marshall, M. D., Leung, H. O., Scheetz, B. Q., Thaler, J. E., Muenter, J. S. "A Chirped Pulse Fourier Transform Microwave Study of the Refrigerant Alternative 2,3,3,3-Tetrafluoropropene," J. Mol. Spec. 2011, 266, 37.
Theulé, P., Muenter, J. S., Callegari, A. "Dipole Moment of Water in Highly Vibrationally Excited States: Analysis of Photofragment Quantum-Beat Spectroscopy Measurements Using a Local-Mode Hamiltonian," J. Phys. Chem. A 2009, 113, 13418-13427.
Koch, M., Lanzersdorfer, J., Callegari, C., Muenter, J. S., Ernst, W. E. "Molecular Beam Magnetic Resonance in Doped Helium Nanodroplets. A Setup for Optically Detected ESR/NMR in the Presence of Unresolved Zeeman Splittings," J. Phys. Chem. A 2009, 113, 13347-13356.
Theulé, P., Callegari, A., Rizzo, T. R., Muenter, J. S. "Dipole Moments of HDO in Highly Excited Vibrational States Measured by Stark Induced Photofragment Quantum Beat Spectroscopy," J. Chem. Phys. 2005, 122, 124312.
Theulé, P., Callegari, A., Rizzo, T. R., Muenter, J. S. "Fluorescence Detected Microwave Stark Effect Measurements in Excited Vibrational States of H2CO," J. Chem. Phys. 2003, 119, 8910-8915.
Callegari, A., Theulé, P., Schmied, R., Rizzo, T. R., Muenter, J. S. "The Dipole Moment of HOCl in vOH=4," J. Mol. Spectrosc. 2003, 221, 116-120.
Callegari, A., Theulé, P., Muenter, J. S., Tolchenov, R. N., Zobov, N. F., Polyansky, O. L., Tennyson, J., Rizzo, T. R. "Dipole Moments of Highly Vibrationally Excited Water," Science 2002, 297, 993-995.
Muenter, J. S., Rebstein, J., Callegari, A., Rizzo, T. R. "Photodissociation Detection of Microwave Transitions in Highly Excited Vibrational States," J. Chem. Phys. 1999, 111, 3488.
Callegari, A., Rebstein, J., Muenter, J. S., Jost, R., Rizzo, T. R. "The Spectroscopy and IVR Dynamics of HOCl in the nOH=6 Region, Probed by Infrared-Visible Double Resonance Overtone Excitation," J. Chem. Phys. 1999, 111, 123.
Muenter, J. S., Bhattacharjee, R. "The Electric Dipole Moment of the CO2-CO van der Waals Complex," J. Mol. Spec. 1998, 109, 290-293.
Marshall, M. D., Izgi, K.C., Muenter, J. S. "IR-Microwave Double Resonance Studies of Dipole Moments in the n1 and n3 States of Ammonia," J. Chem. Phys. 1997, 107, 1037.
Marshall, M. D., Izgi, K. C., Muenter, J. S. "IR-RF Double Resonance Studies of Dipole Moments in the n1 + n 4 and n1 + n5 States of Acetylene-d," J. Chem. Phys. 1996, 105, 7904.
Connoly, J. P., Duxson, S. P., Kennedy, S. K., Howard, B. J., Muenter, J. S. "Hyperfine and Tunneling Effects in the Microwave Spectrum of N2-OCS," J. Mol. Spec. 1996, 175, 85.
Muenter, J. S., Deutsch, J. L. "The Nitrogen Laser Excited Luminescence of Pyrene: A Student Laboratory Study of Excimer Dynamics," J. Chem. Ed. 1996, 73, 580.
Muenter, J. S. "The He-Ne Laser Induced Fluorescence Spectrum of Molecular Iodine: An Undergraduate Laboratory Experiment," J. Chem. Ed. 1996, 73, 576.
Connelly, J. P., Duxon, S. P., Kennedy, S. K., Howard, B. J., Muenter, J. S. "Hyperfine and Tunnelling Effects in the Microwave Spectrum of N2-OCS," J. Mol. Spec. 1996, 170, 85.
Muenter, J. S. "Potential Functions for Carbon Dioxide-Hydrogen Halide and Hydrogen Halide Dimer van der Waals Complexes," J. Chem. Phys. 1995, 103, 1263.