1. THE ZEEMAN EFFECT IN THE OPTICAL SPECTRUM OF MANGANESE MONOHYDRIDE: MnH. Jamie Gengler and Timothy C. Steimle Department of Chemistry and Biochemistry Arizona State University Tempe, AZ 85287-1604 June 18, 2007 Michael Stoll Molecular Physics Fritz-Haber-Institut der Max-Planck-Gessellschaft Faradayweg 4-6, 14195 Berlin, Germany

2. Motivation. J.D. Weinstein, R. deCarvalho, T. Guillet, B. Friederich, and J.M. Doyle, Nature (London), 395, 148-150 (1998). Magnetic trapping of molecules. Ideal candidates have: 1)Unpaired electrons (free- radicals) for nonzero magnetic moment. 2)Large rotational constant for well separated spectral features (diatomic hydrides). So far, NH and CaH have been successfully trapped.

3. 1) Optical A-X (0,0) transition near 17500 cm -1 is ideal for LIF monitoring of magnetic trap spatial and temporal MnH concentrations. 2) X 7  + and A 7  states have  s = 6  B. 3) Rotational constants of B(X 7  + ) = 5.606 cm -1 and B(A 7  ) = 6.348 cm -1. 4) The X 7  + state has much smaller fine-structure parameters of = -0.004 cm -1 and  = 0.03 cm -1. MnH Considerations. 5) The spectra is complicated by hyperfine interactions from both the 55 Mn (I = 5/2) and 1 H (I = 1/2) nuclei.

4. 10 -6 torr diffusion pump 10 -5 torr diffusion pump Mn rod (rotated by stepper motor) 20 Hz Nd:YAG 355 nm (10mJ) CW Ring- Dye Laser PMT Lens Optical filter Mirror Molecular beam 20 Hz solenoid pulsed valve pre-amp Gated photon counter IEEE computer board * * * D/A computer board * * (variable time delay) Burleigh wavemeter RS232 serial computer board I 2, etalon * H 2 300 psi Helmholtz coils Laser Induced Fluorescence.

5. Helmholtz coils (electromagnet) Polarization of the laser can be rotated by 90 0 for parallel “||” or perpendicular “ ┴ ” orientation. Magnetic Fields.

6. Zeeman Spectra. Model T ROT =100 K FWHM=75 MHz P 1 (0) Field- Free 17568.117568.217568.317568.417568.517568.617568.7 Laser Wavenumber (cm -1 )

7. Zeeman Spectra. P 1 (0) Field- Free 17568.117568.217568.317568.417568.517568.617568.7 Laser Wavenumber (cm -1 ) Model T ROT =100 K FWHM=75 MHz

8. Quadrupole Magnet 2.3 T Trap depth: 0.67 K  B -1 T -1 Buffer-gas loading Freezing out of buffer-gas t ~ 5 s Copper cell Magnet 3He/4He-Dilution refrigerator for reaching the mK regime base temperature: 100 mK Magnetic Trapping.

11. Conclusions / Future Work. 1) Molecular beam data closely modeled by simple Zeeman Hamiltonian (RMS ~ 100 MHz, no significant perturbations). 2) Continue refining Zeeman model. Possible inclusion of other branch features and/or anisotropic g-factors. 3) Successful demonstration of magnetically trapping MnH. 4) Determine both elastic and inelastic cross-sections. 5) THANK YOU!!