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 fr Struktur und Dynamik der Materie, Hamburg General Technique Fourier Transform Microwave Spectroscopy Fourier Transform +Microwaves Fourier Transform Microwave Spectroscopy Chirped Pulse 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 Brown et. Al., Rev. Sci. Instrum. 79, 053103 Cavity Based FTMW 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 Grabow et al., Rev. Sci. Instrum. 76, 093106 (200 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
Z eff pv 100 5 ( ) M. Quack, Angew. Chem. 114 (2002) 4812 Target molecules CpRe(CO)(NO)I Two heavy atoms C Predicted Enantiomeric
Enantiomer separation Pmay . Schwerdtfeger, J. Gierlich, T. be difficult Bollwein, Angew. Chem. Int. Ed. 42 (2003) 1293. P. Schwerdtfeger, R. Bast, J. Am. [1] C C C Re Energy difference: 316 Hz[1]
C N O I C O Prof. Dr. Robert Wolf Universitt Regensburg Target molecules Ab initio Rotational Constants A=759.9 MHz
B=423.2 MHz C=379.4 MHz Rotational Temp=0.5 K Re (62.6%) Spin = +5/2 185 Re (37.4%) Spin = +5/2 187 I, Spin = +5/2 14 N, Spin = +1 127
Re Simulation Re Simulation 187 185 CpRe(CO)(NO)(CH3) Results Re (62.6%), Spin = FTMW +5/2 185 Re (37.4%), Spin = +5/2 14 N, Spin = +1 187 Chirped Pulse Broadband
Nuclear Quadrupoles IN en tu m J+IRe=F1 F1+IN=F ul ar m om IRe
= F J To ta la ng F1 Quantum Numbers: J, Ka, Kc, F1, F Ratio of 185Re / 187 Re
Mass = 98.9% A,B,C = 100.003% Rhenium Nuclear Quadrupole Hyperfine Splitting Nitrogen Nuclear Quadrupole Hyperfine Splitting Results Cavity 600 mm mirrors 1 m separation 1 metre 6-40 GHz 1 MHz modes
Resolution 1 kHz Require <10 Hz Resolution v=30-50 m/s v=30-50 m/s Doppler width 1 kHz at 10 GHz v=30-50 m/s v=15-20 m/s Transit time broadening 150 Hz Helium Buffer Gas
Chamber at 4 K John Doyle and Dave Patterson - Harvard University (Unpublished) Or: Microwave focussing and deceleration Merz et.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 Characterisation of heavy molecules Parity violation Preliminary Results CpRe(NO)(CO)(CH3) Acknowledgements FD
02 WA 03 Thomas Betz Chris Medcraft Alvin Shubert Melanie Schnell FD 05 Sabrina Zinn Simon
Merz Jack Graneek David Schmitz Acknowledgements Robert Wolf - Universitt Regensburg Jens-Uwe Grabow - Leibniz Universitt Hannover Slow molecules v=30-50 m/s v=1-3 m/s vDoppler=15-100 Hz vtransit 3 Hz Electronics
ab and bc No Off-diagonal Re NQCC 2 1.8 1.6 RMS Error / MHz 1.4 1.2 1 0.8 0.6 0.4 0.2 0
No 2nd order Noterms off- diagon al Chi_ab ab Chi_ab, Chi_ab, Chi_bc, Chi_ac , Chi_bc ab bc
ab , bc, ac Calculations Rhenium (Z=75) Lots of electrons! Requires relativistic correction ANORCC* 2 ANORCC with DKH 1.5
1 0.5 N bb-cc N aa Re ab Re bb-cc C 0 Re aa Methyl Cyclopentadienyl
2.5 B Internal rotations Basis Set 3 A Cant use pseudopotentials Large off diagonal terms for Rhenium 3.5
Observed/Calc Nuclear quadrupole coupling 4 SARC *no relativistic correction
