Characterisation and Control of Cold Chiral Compounds Chris Medcraft “Structure and Dynamics of Cold and Controlled Molecules” Center for Free-Electron Laser Science, Hamburg Max-Planck-Institut für Struktur und Dynamik der Materie, Hamburg

General Technique Fourier Transform Microwave Spectroscopy

Fourier Transform Microwave Spectroscopy Chirped Pulse FTMW Cavity Based FTMW Chirped Excitation signal 2-8.5 GHz from AWG 300W TWT Amplifier Molecular response measured directly by fast oscilloscope Full spectrum in one shot ≈ 40 kHz resolution Cavity resonance amplifies excitation and molecule signals 6-40 GHz range Molecular response mixed down to radio frequency 1 MHz of spectrum measured at once ≈1 kHz resolution Brown et. Al., Rev. Sci. Instrum. 79, 053103 (2008) Grabow et al., Rev. Sci. Instrum. 76, 093106 (2005)

Chiral Molecules to study Parity Violation Arises from the weak interaction Test of fundamental physics Small difference in energy between enantiomers Measureable difference in rotational transitions Large atoms increase the effect dramatically Δ pv ∝ Z eff 100 5 M. Quack, Angew. Chem. 114 (2002) 4812

Universität Regensburg Target molecules CpRe(CO)(NO)I Two heavy atoms Predicted Enantiomeric Energy difference: 316 Hz[1] Enantiomer separation may be difficult Re I N O C Prof. Dr. Robert Wolf Universität Regensburg [1]P. Schwerdtfeger, J. Gierlich, T. Bollwein, Angew. Chem. Int. Ed. 42 (2003) 1293. P. Schwerdtfeger, R. Bast, J. Am. Chem. Soc. 126 (2004) 1652.

Target molecules 187Re (62.6%) Spin = +5/2 185Re (37.4%) 127I, Spin = +5/2 14N, Spin = +1 Ab initio Rotational Constants A=759.9 MHz B=423.2 MHz C=379.4 MHz Rotational Temp=0.5 K 187Re Simulation 185Re Simulation

CpRe(CO)(NO)(CH3) Results 187Re (62.6%), Spin = +5/2 185Re (37.4%), Spin = +5/2 14N, Spin = +1 Chirped Pulse Broadband FTMW

Nuclear Quadrupoles J+IRe=F1 F1+IN=F Ratio of 185Re / 187Re Quantum Numbers: J, Ka, Kc, F1, F F1 F = Total angular momentum Ratio of 185Re / 187Re Mass = 98.9% A,B,C = 100.003% Q = 105.5% J

Rhenium Nuclear Quadrupole Hyperfine Splitting

Nitrogen Nuclear Quadrupole Hyperfine Splitting

Results

Cavity 600 mm mirrors 1 m separation 6-40 GHz 1 MHz modes Resolution ≈1 kHz Require <10 Hz 1 metre

Transit time broadening ≈ 150 Hz Resolution Doppler width ≈1 kHz at 10 GHz δv=30-50 m/s δv=15-20 m/s Transit time broadening ≈ 150 Hz

Helium Buffer Gas Or: Microwave focussing and deceleration Chamber at ≈ 4 K John Doyle and Dave Patterson - Harvard University (Unpublished) Or: Microwave focussing and deceleration Merz et. al., Phys. Rev. A 85, 063411 

Summary Experimental design Aims Preliminary Results Characterisation of heavy molecules Parity violation Preliminary Results CpRe(NO)(CO)(CH3)

Acknowledgements FD02 WA 03 Chris Medcraft Thomas Betz Alvin Shubert Melanie Schnell FD05 Simon Merz Jack Graneek Sabrina Zinn David Schmitz

Acknowledgements Robert Wolf - Universität Regensburg Jens-Uwe Grabow - Leibniz Universität Hannover

Slow molecules δv=1-3 m/s vDoppler=15-100 Hz vtransit ≈ 3 Hz

Electronics

No Off-diagonal Re NQCC χab and χbc χab , χbc

Calculations Rhenium (Z=75) Nuclear quadrupole coupling Lots of electrons! Requires relativistic correction Nuclear quadrupole coupling Can’t use pseudopotentials Large off diagonal terms for Rhenium Internal rotations Methyl Cyclopentadienyl Basis Set *no relativistic correction