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 UMSL 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: B 420
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.
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.
Spectrum derived from high-resolution ILS measurements on methane at 2 to 30 torr.

ILS spectrum for the atmospheric A-band of O2

ILS spectrum for the atmospheric A-band of O2

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

″Rotational and deperturbation analysis of the (0,0) and (1,0) vibrational bands of the [15.30]1 – X 3Σ–(0+) transition of WS″,  K. N. Bales, J. C. Harms, J. J. O’Brien and L. C. O’Brien, J. Mol. Spectrosc. 2022, 389, 111702.

″Analysis of the newly observed [15.05]0+ – X 3R–(0+) transition of WS observed using intracavity laser spectroscopy with Fourier-transform detection″, K. N. Bales, J. C. Harms, J. J. O’Brien and L. C. O’Brien, J. Mol. Spectrosc. 2021, 377, 111430.

″Analysis of the (0,0) band of the new [15.3]Ω=3/2 – X 2Π3/2 electronic transition of PtF using intracavity laser spectroscopy″, C. A. Welch, J. A. Harms, J. J. O′Brien and L. C. O′Brien, J. Mol. Spectrosc. 2021, 380, 111517.

″Observation and analysis of a new [14.26]0+ – X 3R–0+ transition of WS, observed using intracavity laser spectroscopy with Fourier-transform detection″, J. C. Harms K. N. Bales, J. C. Harms, J. J. O’Brien and L. C. O’Brien, J. Mol. Spectrosc. 2020, 374, 111378. 

″Intracavity laser spectroscopy with Fourier-transform detection of tungsten sulfide, WS: Analysis of the (1,0) band of the [13.10] X = 1 _ X 3R–0+ transition″, J. C. Harms, B. M. Rataya, K. N. Bales, J. C. Harms, J. J. O’Brien and L. C. O’Brien, J. Mol. Spectrosc. 2020, 372, 111349

″Analysis of the A Ω=1 - X3Σ-0+ transition of PtS observed by intracavity laser spectroscopy with fourier transform detection (ILS-FTS), and computational studies of electronic states of PtS″, L. C. OʹBrien, J. C. Harms, J. J. OʹBrien and W. Zou, J. Mol. Struct., 2020, 1211, 128024.

″Identification of two new electronic transitions of TaF using intracavity laser spectroscopy″, K. N. Bales, J. C. Harms, L. C. OʹBrien and J. J. OʹBrien J. Mol. Spectrosc. 2019, 365, 111208

″Rotational analysis of the [15.1] A''-X~1A' transition of CuOH and CuOD observed at high resolution with Intracavity laser spectroscopy,″ J. C. Harms, J. L. C. O'Brien and J. J. O'Brien, J. Mol. Spectrosc. 2019, 362, 8.

″Mass-independent Dunham analysis of the known electronic states of platinum sulfide, PtS, and analysis of the electronic field-shift effect,″ J. C. Harms, L. C.; O'Brien and J. J. O'Brien, J. Chem. Phy. 2019, 151, 094303.

″Mass-independent dunham analysis of the [7.7] Y2Σ+ - X2Πi and [16.3] A2Σ- - X2Πi transitions of copper monoxide, CuO,″ J. C. Harms, E. M. Grames, S. Yun, B. Ahmed, L. C. O'Brien and J. J. O'Brien, J. Mol. Spectrosc. 2019, 363, 111173

″Identification of two new electronic transitions of TaF using intracavity laser spectroscopy″ K. N. Bales, J. C. Harms, L. C. O’Brien and J. J. O’Brien, J. Mol. Spectrosc. 2019, 365, 111208.

″Mass-independent Dunham analysis of the [13.8] Ω = 3/2 - X2Π3/2 transition of platinum monochloride, PtCl, observed by intracavity laser spectroscopy: Periodic trends in the M+X- bonding model (M = Ni, Pt; X = F, Cl),″ J. C. Harms, J. Wu, S. Mian, L. C. O'Brien and J. J. O'Brien, J. Mol. Spectrosc. 2019, 359, 6.

″Identification and characterization of two new electronic states of PtF: Analysis of the (2,1), (1,0), (0,0), (0,1), (1,2), and (0,2) bands of the [15.8 + x] Ω = 5/2 - B2Δ5/2 transition, ″ J. C.  Harms, L. C. O'Brien and J. J. O'Brien, J. Mol.  Spectrosc. 2019, 355, 101.

″The spin-forbidden a 4Σ−–X 2Π1/2 transition of GeH detected in absorption using intracavity laser spectroscopy,″ J. C. Harms, L. C. O’Brien and J. J. O’Brien, J. Chem Phys. 2018, 148, 204306

″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.