Research in the Bartz laboratory focuses on photodissociation studies of NO-containing organometallic and organic compounds. Students in the lab use Nd:YAG-pumped dye lasers to photodissociate gas phase molecules and determine the vector correlations between and among the transition dipole (mu), recoil velocity (v), and angular momentum (J).

Velocity-Mapped Ion Imaging

Velocity-Mapped Ion Imaging (VMII) is a mass spectrometric technique where the initial product recoil velocity is mapped onto a 2-d detector. The mass spectrometer is housed in a high vacuum system with a base pressure of <10-7 torr. The molecules are carried into the mass spectrometer in a He carrier gas through a pulsed nozzle.

Fig 1. Schematic of a VMII instrument

Laser scheme

In our laboratory, we use a three-color laser technique. The first laser pulse dissociates the target molecule. The second laser (224 - 227 nm) excites the newly-formed NO products in the X --> A transition. The third pulse (308 nm) ionizes the excited NO products.

Ion detection

The NO+ ions are accelerated by the ion optics. They travel through a field-free region and strike a multichannel plate detector. The ion positions are detected as spots of light on a phosphor screen by a cooled CCD camera. The laboratory computer collects each of the ion images separately, determines the position of each ion, and stores the images on the hard drive.

Publications

1. 1.J.A. Bartz, S. Odawara, S.A. Collier, K.M. Meisel, K.P. Burke, J.J. Cekola, and G.E. Leroi.  "NO (v"=0) rotational distributions from the photodissociation of organometallic nitrosyls in the charge transfer region." J. Phys. Chem. A 105, 319 (2001).
   

2. 2.J.A. Bartz, S.C. Everhart, and J.I. Cline.  “Determination of the v-j vector correlation in the photodissociation of nitrosobenzene at 305 nm.” J. Chem. Phys. 132, 074310 (2010).
   

3. 3.A.L. Peden, R.D. Kieda, K.A. Breck, J.R. Basore, C.A. Kent, and J.A. Bartz. “UV Photodissociation of η5-C5H5NiNO: A Jahn-Teller Excited-State Distortion Produces a Cartwheeling NO.” J. Phys. Chem. A, 114, 10922 (2010).
   

4. 4.M.P. Grubb, M.L. Warter, C.D. Freeman, N.A. West, K.M. Usakoski, K.M. Johnson, J.A. Bartz, and S.W. North. “A method for the determination of speed-dependent semi-classical vector correlations from sliced image anisotropies.” J. Chem. Phys., 135, 094201 (2011).
   

5. 5.M. Hossain, A.J. Klobuchar, and J.A. Bartz, The photodissociation of N,N-dimethylnitrosamine at 355 nm: The effect of excited-state conformational changes on product vector correlations. J. Chem. Phys., 2017, 147, 013925.
   

6. 6.Fairhall, A. J.; Orlando, M. M.; Bartz, J. A. 355 nm Photodissociation of N2O3 Revealed by Velocity-Mapped Ion Imaging. J. Phys. Chem. A 2020, 124, 472-478. DOI:10.1021/acs.jpca.9b08688