Direct Detection Transit Astrometry Doppler Spectroscopy Detection of Circumstellar Disks
Sub-Doppler Spectroscopy of H 3 +
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Sub-Doppler Spectroscopy of H 3 + James N. Hodges , Adam J. Perry, Brian M. Siller, Benjamin J. McCall
description
Sub-Doppler Spectroscopy of H 3 +. James N. Hodges , Adam J. Perry, Brian M. Siller , Benjamin J. McCall. Outline. Motivation Fundamental Physics Astronomy Instrument Description Transition Frequency Results Wavelength Calibration Testing. H 3 + Fundamental Benchmark. - PowerPoint PPT Presentation
Transcript of Sub-Doppler Spectroscopy of H 3 +
Sub-Doppler Spectroscopy of H3+
James N. Hodges, Adam J. Perry, Brian M. Siller, Benjamin J. McCall
Outline
• Motivation– Fundamental Physics– Astronomy
• Instrument Description• Transition Frequency Results• Wavelength Calibration Testing
H3+ Fundamental Benchmark
• Simplest polyatomic ion• Benchmark for ab initio theory
– Accuracy of order 300 MHz @ low energy
• QED corrections are frontier– Accuracy of order 30 MHz @ low energy
• Requires higher precision data
O. L. Polyansky, J. Tennyson, J. Chem. Phys. (1999), 110, 5056-5064.J. Komasa, et al. J. Chem. Theor. Comp. (2011), 7, 3105-3115.
H3+ Astronomically Important
• Abundant in Interstellar Medium• Deuterium Fractionation• Found in Ionospheres of Gas
Giants• Measure Speed of Auroral Winds • Limited by Laboratory Accuracy
T. R. Geballe and T. Oka, Nature (1996), 384, 334.P. Drossart et al. Nature (1989), 340, 539.D. Rego et al. Nature (1999), 399, 121.
Images From: http://solarsystem.nasa.gov/planets/profile.cfm?Object=Jupiterhttp://www.ucl.ac.uk/~ucaptss/work/publications/royalsoc/energy.htm
Spectroscopic TechniqueLarge Signal
Low Noise
Ion Selectivity
Cavity Enhancement
Heterodyne Spectroscopy
Velocity Modulation
NICE-OHVMS
Noise Immune Cavity Enhanced Optical Heterodyne Velocity Modulation Spectroscopy
B. M. Siller, et al. Opt. Express (2011), 19, 24822-7.
Instrumental Layout
OPO
YDFL
EOMLock-In
Amplifier
X & YSignal
Lock-In Amplifier
X & YSignal
Wave-meter
40 kHzPlasma
Frequency
80 MHz1 × Cavity Free Spectral Range
90o Phase Shift
IPS
2f
ni = np - ns
Freq. CombAOM
K. N. Crabtree, et al. Chem. Phys. Lett. (2012), 551, 1-6.
Comb Calibration
Wave-meter
Freq. CombAOM
[…]
Signal Pump
Comb Calibration
Wave-meter
Freq. CombAOM
[…]
Signal Pump
Comb Calibration
Wave-meter
Freq. CombAOM
[…]
Signal PumpSignal
H3+ Spectra
Sig
nal
Signal
Doubly Degenerate n2 Band
H3+ Transition Notation
𝐺≡|𝑘− 𝑙|{𝑃∨𝑄∨𝑅 }( 𝐽 ,𝐺){𝑢∨𝑙 }
Lamb Dips & Saturation• High Power Optical Saturation Lamb dips• Second Comb Calibrated Observation of Lamb dips
• In NICE-OHVMS fm-triplet causes many Lamb dips
H.-C. Chen et al. Phys. Rev. Lett. (2012), 109, 263002.K.N. Crabtree et al. Chem. Phys. Lett. (2012), 551, 1.
Lamb Dips & Saturation• High Power Optical Saturation Lamb dips• Second Comb Calibrated Observation of Lamb dips
• In NICE-OHVMS fm-triplet causes many Lamb dips
H.-C. Chen et al. Phys. Rev. Lett. (2012), 109, 263002.K.N. Crabtree et al. Chem. Phys. Lett. (2012), 551, 1.
Lamb Dips & Saturation• High Power Optical Saturation Lamb dips• Second Comb Calibrated Observation of Lamb dips
• In NICE-OHVMS fm-triplet causes many Lamb dips
H.-C. Chen et al. Phys. Rev. Lett. (2012), 109, 263002.K.N. Crabtree et al. Chem. Phys. Lett. (2012), 551, 1.
Lamb Dips & Saturation• High Power Optical Saturation Lamb dips• Second Comb Calibrated Observation of Lamb dips
• In NICE-OHVMS fm-triplet causes many Lamb dips
H.-C. Chen et al. Phys. Rev. Lett. (2012), 109, 263002.K.N. Crabtree et al. Chem. Phys. Lett. (2012), 551, 1.
Lamb Dips and Fits
R(2,2)l Transition
Transition Frequencies
𝜎 𝜇=𝜎√𝑛
St. Err. = St. Dev. Of Mean
Lamb Dip Signal-to-Noise-RatioLamb Dip SNR:
𝑆𝑁𝑅=𝑆𝑖𝑔𝑛𝑎𝑙𝑝𝑘−𝑝𝑘𝜎𝑟𝑒𝑠𝑖𝑑𝑢𝑎𝑙𝑠
Lamb Dip Signal-to-Noise-Ratio
R(1,0)R(3,2)l
Frequency Calibration Test
• First use of a comb with this instrument• Need to ensure proper calibration• Lamb dips of methane
Instrumental Layout
OPO
YDFL
EOMLock-In
Amplifier
X & YSignal
Lock-In Amplifier
X & YSignal
Wave-meter
40 kHzPlasma
Frequency
80 MHz1 × Cavity Free Spectral Range
90o Phase Shift
IPS
2f
ni = np - ns
Freq. CombAOM
1.4 kHzModulationFrequency
3f
Frequency Calibration Test
• First use of a comb with this instrument• Need to ensure proper calibration• Lamb dips of methane• Acquired Lamb dips for F1
(2) component of P(7) transition of n3 band
Frequency Calibration Test
Lamb dip of methaneFit with 2nd derivative of Lorentzian
5 kHz diff. from Takahata et al. ~30 kHz st. dev. from fit
K. Takahata et al. Phys. Rev. A. (2009) 80, 032518.
ConclusionsComb calibrated H3
+ transitions reported
Higher S/N lines have sub-MHz precision
Methane used to validate comb calibration
Values differ than Chen et al. H.-C. Chen et al. Phys. Rev. Lett. (2012), 109, 263002.
Acknowledgements
Springborn FellowshipNSF GRF (DGE 11-44245 FLLW)
