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James J. O'Brien

James J. O'Brien

Dr. 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.
Office: M 105
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

″Identification of two new excited electronic states of NiCl: Analyses of the (1,0) & (0,0) bands of the [13.5] 2Φ7/2 -[0.16] A2Δ5/2 and (0,0) band of the [13.8] 2Π1/2 - [0.38] X2Π1/2 transitions,″ J. C. Harms, E. M. Grames, S. Han, L. C. O'Brien and J. J. O’Brien, J. Mol. Spectrosc. 2017, 333, 36.

″The near-infrared spectrum of NiCl: Analysis of vibrational components of system G and system H between 12,500 cm-1 and 13,750 cm-1,″ J. C. Harms, C. N. Gipson, E. M.  Grames, J. J. O'Brien and L. C. O'Brien, J. Mol. Spectrosc. 2016, 321,78.

″Near-infrared spectrum of ZrF by intracavity laser absorption spectroscopy″, J. C. Harms, L. C. O’Brien, A. Ni, B. Nahkdoom and J. J. O’Brien, J. Mol. Spectrosc. 2015, 310, 68

High resolution electronic spectroscopy of the A2Σ- - X2Π1/2 transition of PtN,” K. Womack, L. C. O'Brien, S. Whittemore, J. J. O’Brien, A. Li, and T. C. Steimle, J. Chem. Phys. 2014, 141, 084304/1

"Improved experimental line positions for the (1, 1) band of the b1S+-X3S transition of O2," J. J. O'Brien, E. C. O'Brien and L. C. O'Brien, J. Mol. Spectrosc. 2012, 273, 34.

"Intracavity laser absorption spectroscopy of platinum fluoride, PtF," K. Handler, R. A. Harris, L. C. OBrien, and J. J. OBrien, J. Mol. Spectrosc. 2011, 265, 39.

"The 5-0 overtone band of HCl," J. J. O'Brien, S. A. Ryan and L. C. O'Brien, J. Mol. Spectrosc.2011, 265, 110.

"The Pt2 (1,0) Band of System VI in the Near Infrared by Intracavity Laser Absorption Spectroscopy," L. C. O'Brien and J. J. O'Brien J. Chem. Phys. 2011, 134,184304/1.

"Chemically deposited Sb2S3 thin films for optical recording," S. Shaji, A. Arato, J. J. O'Brien, J. Liu, G. Alan Castillo, M. I. Mendivil Palma, T. K. Das Roy and B. Krishnan, J. Phys. D: Appl. Phys. 2010, 43, 075404/1

"Intracavity laser absorption spectroscopy of platinum sulfide in the near infrared," K. Handler, L. C. O'Brien and J. J. O'Brien, J. Mol. Spectrosc. 2010, 263, 78. 

"Spectroscopy of NiF by intracavity laser spectroscopy: Identification and analysis of the (1,0) band of the [11.1] 2P3/2-X 2P3/2 electronic transition," R. A. Harris, L. C. O'Brien and J. J. O'Brien, J. Mol. Spectrosc. 2010259, 116.   

"Sb2S3:C/CdS p-n junction by laser irradiation,"  A.  Arato, E. Cardenas, S. Shaji, J. J. O'Brien, J. Liu, A. G..Castillo, T. K. Das Roy and B. Krishnan, Thin Solid Films 2009, 517, 2493.

"Laboratory measurements of the (2,0) B2D5/2-X2D5/2 transition of nickel hydride using intracavity laser absorption spectroscopy," S. Shaji, A. Song, M. Li, J. J. O'Brien and L. C. O'Brien, Can. J. Phys200987, 583

"Spectroscopy of PtO by intra-cavity laser spectroscopy: Identification of the A30+ -x1 electronic transition," H. Liu, L. C. O'Brien, S. Shaji and J. J. O'Brien, J. Mol. Spectrosc.2009253, 73.