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James J. O'Brien

James J. O'BrienDr. O'Brien received his B.Sc. (Hons) from James Cook University, and his Ph.D. degree from the Australian National University. He joined UM-St. Louis after postdoctoral positions at the University of California-Berkeley, the National Research Council of Canada, and the University of Arizona.

 

obrien@jinx.umsl.edu
Office:  B414
Phone: (314) 516-5717
Fax:    (314) 516-5342

Research Interests

Jim O’Brien is an experimental physical chemist who specializes in fundamental and applied, high-resolution laser spectroscopy and gas phase analytical chemistry. The primary tool employed is Intracavity Laser Spectroscopy. ILS techniques provide tremendously enhanced sensitivity for obtaining quantitative absorption spectra. Research areas include: (1) the acquisition of quantitative absorption spectroscopy parameters (e.g., absorption coefficients for methane in the visible to near-IR spectral region to assist in interpreting spectra of the outer planets such as Neptune and line positions for the high-resolution spectrum of molecular O2 for visible and near-IR bands; (2) high-resolution electronic spectroscopy of small molecules (e.g., CuCl, NiCl, NiH) with a view to locating excited electronic states in these species; (3) the gas phase chemistries and species involved in a variety of chemical vapor deposition (CVD) processes (e.g., the plasma deposition of films of diamond-like carbon (DLC), diamond-like nanocomposites (DLN), and silicon oxide); and (4) the further development of the intracavity laser spectroscopy (ILS) technique for analytical purposes (e.g., in acquiring spectra at ultra-high spectral resolution) and its range of applications (e.g., extension of ILS into the IR region by use of fiber lasers).

ILS system used for the methane studies conducted at sample temperature of 77 K.

Spectrum derived from high-resolution ILS measurements on methane at 2 to 30 torr.

 

 

ILS spectrum for the atmospheric A-band of O2.  The spectrum in the left panel is normalized to 3 torr and that in the right panel is normalized to 30 torr.  Many of the lines in the right panel spectrum are saturated but many more lines in the band can be observed under these conditions.

Selected Publications

"Intracavity laser absorption spectra of nickel hydride",   S. Shaji, J. Nunn, J. J. O'Brien, L. C. O'Brien, Astrophysical Journal, 2008,  672,  722

"Intracavity laser absorption spectroscopy of AuO: Identification of the b 4P3/2-X 2P3/2 transition" , S. Shaji, A. Song, J. J. O'Brien, B. A. Borchert and L. C. O'Brien, J. Mol. Spectrosc. 2007, 243, 37.

"Fourier transform spectroscopy of NiCl. Identification of the [10.3] 4F7/2 state", K. D. Gibbs, D. J. Trader, L. C. O'Brien and J. J. O'Brien, J. Mol. Spectros., 2006, 240 , 64.

"Spectroscopy of nickel chloride: Identification of the [15.0] 2P3/2 and [15.0] 2D5/2 states", J. W-H. Leung, J. Ye, A. S-C. Cheung, K. D. Gibbs, D. L. Palmer, L. C. O'Brien and J. J. O'Brien, J. Mol. Spectros., 2006, 238, 42.

"Spectroscopy of NiCl: Identification of the X2P1/2 state", C. A. Rice, Corey T. L. Kellerman, B. Owen, L. C. O'Brien, H. Cao and J. J. O'Brien, J. Mol. Spectros., 2006,  235, 271.

"Laboratory measurements of NiH by intracavity laser absorption spectroscopy", L. C. O'Brien and J. J. O'Brien, Astrophys. Journal, 2005, 621, 554.

"Spectroscopy of AuO: Identification of the [10.7] P 3/2 to X2P3/2 Transition", L. C. O'Brien, S. C. Hardimon and J. J. O'Brien, J. Phys. Chem. A, 2004, 108, 11302.

"Fourier transform spectroscopy of NiCl: identification of a [9.1] W = 3/2 state", S. Tumturk, L. C. O'Brien and J. J. O'Brien, J. Mol. Spectros., 2004, 225, 225.

"Absorption spectra and absorption coefficients for methane in the 750-940 nm region obtained by intracavity laser spectroscopy", J. J. O'Brien and H. Cao, Journal of Quantitative Spectroscopy and Radiative Transfer, 2002, 75, 323.

"Fourier Transform and Intracavity Laser Spectroscopy of NiCl System H: Identification of a [12.3] 2S+ State", L. C. O’Brien, K.M. Homann, T.L. Kellerman, and James J. O’Brien; Journal of Molecular Spectroscopy, 2002, 211, 93. 

"Intracavity Laser Spectroscopy of NiCl System G: Identification of a [13.0] 2P3/2 State", J. J. O’Brien, J. S. Miller and L. C. O’Brien, Journal of Molecular Spectroscopy, 2002, 211, 248.

"Molecular constants for the v=0, b 1S+g derived from measurements of the spectroscopy", L. C. O'Brien, H. Cao, and J. J. O'Brien, Journal of Molecular Spectroscopy, 2001, 207, 99.

"The Near-Infrared Transition of CuCl Observed by Intracavity Laser Spectroscopy", L. C. O'Brien, H. Cao, and J. J. O'Brien, Journal of Molecular Spectroscopy, 2000, 199, 100.

"Quantitative Intracavity Laser Spectroscopy Measurements with a Ti:sapphire Laser:  Absorption Intensities for Water Lines in the 790-800 nm Region", B. Kalmar and J. J. O'Brien, Journal of Molecular Spectroscopy, 1998, 192, 386.

 "Automated gate valve operation for pressure control",    H. C. Barshilia, B. Kalmar, N. R Windsor, G. Kershmann, J. J. O'Brien, Review of Scientific Instruments 1998,  69,  496.