Frequency Comb VelocityModulation Spectroscopy of Hf F Kevin

Frequency Comb Velocity-Modulation Spectroscopy of Hf. F+ Kevin Cossel Laura Sinclair, Tyler Coffey, Jun Ye, and Eric Cornell OSU 2011 Acknowledgements: Huanqian Loh, Matt Grau (JILA) John Bohn, Ed Meyer (JILA) A. Petrov, A. Titov (Petersburg Nuc Phys Inst) Bob Field (MIT) Funding: NSF and the W. M. Keck Foundation

Electron Electric Dipole Moment (e. EDM) search • 3 D 1 metastable state of Hf. F+ and Th. F+ provides high sensitivity (Hf 6 s 15 d 1) Up to 2000 cm-1 uncertainty E. Meyer, et. al. Phys. Rev. A 73, 062108 (2006) • Use multiple excited states for state preparation and Recently spin readout measured with PFI-ZEKE • Very little spectroscopic Barker, et al. J data exists for either species Chem. Phys. 134 1 P 1 3 P 1 D 3 D 0 2 3 D 3 D Predicted Hf. F+ Structure 3 2 1 1 S+ 201102 (2011) Need broadband survey spectroscopy of molecular ions! A. Petrov, et al. Phys. Rev. A 76, 030501 (2007) A. Petrov, et al. Phys. Rev. A 79, 012505 (2009)

signal Velocity-Modulation Spectroscopy t 10 k. Hz, 1 k. W n laser Discharge produces and modulates the ions n Review of VMS: Stephenson and Saykally, Chem Rev. 105 (2005) Ion selectivity! Lock-in Detector

Frequency Combs and Cavities Frequency combs provide narrow lines over a wide spectral bandwidth. Cavity Enhancement with a Frequency Comb: Match Spacing of Frequency Comb Modes to Cavity’s Free Spectral Rang e Cavity FSR. . . frep Adler et al. Annu. Rev. Anal. Chem. 3 (2010)

Frequency comb + velocity modulation + cavity 3 GHz comb Ring cavity Finesse ~ 100 FSR ~ 120 MHz VIPA Etalon Vertical dispersion Grating Horizontal dispersion Artwork: B. Baxley/JILA 10 k. Hz, 1 k. W (250 m. A) Lock-in detection on every comb tooth (1500 simultaneous channels)! Heliotis Lock-in Camera S. Beer, P. Seitz, Research in Microelectronics and Electronics, 2005 Ph. D, 2 135 (2005)

Image of comb teeth on lock-in camera DC Intensity ~100 GHz ~3 GHz

Data Analysis: Fit comb teeth positions DC Intensity

Data Analysis: Demodulating Each Comb Mode Signal at 10 k. Hz n

Data Analysis: Scanning 28 images x 1500 simultaneous channels of lock-in detection

Putting it all together: Hf. F+ ! 1 P 1 P 1 1 + 1 S (0, 1) 3 P 1 1 S+ (2, 0) 1 S+ (1, 2) • >500 cm-1 currently covered • 150 cm-1 in under an hour • 3 x 10 -7 fractional sensitivity • 3 bands (over 1000 lines) + still unidentified lines

More Hf. F+ ! Fit for 1 P 1 1 S+ (0, 1) band

Summary of 180 Hf. F+ Fits E(J”, J’) = T 0 + (B’ – P*k’/2)J’(J’+1) - (D’ – P*k. D’/2)J’ 2(J’+1)2 - B”J”(J”+1) + D”J” 2(J”+1)2 For DJ = 0, P = -1; For DJ = ± 1, P = 1 1 P 1 1 S+ (0, 1) 3 P 1 1 S+ (2, 0) 1 P 1 1 S+ (1, 2) T 0 [cm-1] 12217. 388 (2) 12304. 369 (3) 12133. 977 (5) B” [cm-1] 0. 30335 (3) 0. 30481 (4)* 0. 30100 (50) B’ [cm-1] 0. 28115 (3) 0. 28096 (4) 0. 27890 (40) D” [10 -7 cm-1] 1. 88 (8) 1. 78 (12) 4. 3 (4) D’ [10 -7 cm-1] 1. 81 (8) 1. 78 (11) 4. 2 (4) k‘ [10 -4 cm-1] 3. 69 (2) -3. 82 (1) 3. 6 (5) k. D’ [10 -9 cm-1] 9. 7 (0. 7) -0. 3 (1. 0) 14 (15) • Lambda doubling (k’) switches sign between 1 P 1 and 3 P 1 • Need lambda doubling proportional to J 4 (k. D’) only for 1 P 1 * Measured by Barker, et. al. 0. 304(10)

Measured Hf. F+ Electronic Structure 1 P 3 P 1 1 P 1 shifted by 1700 cm-1 from theory 1 700 cm-1 1 - 3 P 1 fine structure splitting = 2100 cm-1 (theory = 2100 cm-1) 1 P 3 1 & P 1 oscillator 1 S+ equal to ~30% strength to 12304. 369 cm-1 12133. 977 cm-1 12217. 388 cm-1 13002. 229 cm-1 700 cm-1 1 S+ 1 P 784. 84 cm-1 consistent with Barker, et al. 785. 8(10) cm-1 Theory: A. Petrov, N. Mosyagin, A. Titov, Phys. Rev. A 79 012505

Conclusions q Demonstrated frequency comb velocity-modulation spectroscopy with: • 4 x 10 -8 Hz-1/2 (spectral element)-1/2 fractional absorption sensitivity • 150 cm-1 spectral coverage with 1500 simultaneous measurements • 30 MHz absolute frequency accuracy q 700 cm-1 covered so far for Hf. F+ (Th. F+ coming soon) q This is a very general technique which given the current frequency comb technology could be extended across wavelengths from the UV to the IR q Other applications: physical chemistry (H 3+, CH 5+), astrochemistry (diffuse interstellar bands)