Shui-Ming Hu （胡水明） University of Science & Technology of China (USTC) Hefei, China June 17, 2014, ISMS-UIUC Doppler broadening thermometry based on cavity ring-down spectroscopy TJ12

Beijing Shanghai Hongkong Where is Hefei?

γDγD ν0ν0 ν Parameter cm ν0ν0 γDγD TkBkB Uncertainty0~ 10 ppb< 1 ppb?1ppm Doppler Broadening Thermometry (DBT) C. Daussy, et al., Phys. Rev. Lett. 98, (2007); C. Lemarchand et al., New J. Phys. 13, (2011). G. Casa, et al., Phys. Rev. Lett. 100, (2008); L. Moretti et al., Phys. Rev. Lett. 111, (2013)

Determination of Boltzmann Constant k B (CODATA2010) AGT: acoustic gas thermometry RIGT: refractive index gas thermometry JNT: Johnson noise thermometry INRIM: Istituto Nazionale di Ricerca Metrologica, Torino, Italy LNE: Laboratoire national de m´etrologie et d’essais,Trappes, France NIST: National Institute of Standards and Technology, USA NPL: National Physical Laboratory, Teddington, UK AGT k B = (13) E-23 J/K Rel. Uncertainty ～ 1ppm

Uncertainty budget in DBT Moretti et al, PRL 111: (2013)  SNR of spectrum, 300 ppm (single scan)  Pressure induced broadening effects, Pa  Laser line width, 1MHz Better sensitivity? Better precision?

Cavity ring-down spectroscopy (CRDS) Very high sensitivity L eff ~ 10,000 km Large dynamic range I =I 0 exp(-t/τ) Timet=0 Intensity τ0τ0 τ

Frequency drift C 2 H 2 ro-vibrational line at 12629cm -1 C 2 H 2 60 Pa

Laser-Locked CRDS Ring-down Cavity Laser Peak Lock ULE-FPI Etalon Lock etalon λ/2 PZT DAQ PD v0v0 Switch EOM v 0 -f m v 0 +f m v0v0 Microwave Pan et al, Rev. Sci. Instrum. 82:103110, 2011

Laser frequency Precision: ~10 kHz Dynamic range: ~10 GHz Absorption coefficient Sensitivity: ~ /cm Dynamic range: >10 5 Sensitivity & Precision of LL-CRDS Freq. combs Freq. Ref. Microwave scan Gao et al, Rev. Sci. Instrum. 81:043105, 2010; Cheng et al, Opt Express, 20:9956, 2012 Pan et al, Rev. Sci. Instrum. 82:103110, 2011

Sun et al, Opt Express 19: (2011)  Higher sensitivity Measurement with low sample pressures  Better precision Scan with microwave  Superior linear dynamic range

Temperature-Stabilized Ring-down Cavity T 1 - T 2 = 0.32(1) mK

AOM 1 AOM 2 MBR110 PBS Pol λ/4 Det2 Det1 Det3 BS ULE-FPI Det4 PZT Hart 5686 Heating wire ～ EOM × v0v0 v 0 -f m v 0 +f m v0v0 T controlled etalon PBS Etalon lock PZT v 0 +f m RF synthesizer GPS-disciplined Rb clock EOM

C 2 H 2 ~3.3Pa 100 s each scan SNR~10,000

Statistical uncertainty in determined line width N: number of scans

DBT Temperature from different line-profile models

USTC Dr. Cun-Feng Cheng Dr. Yu Sun Dr. An-Wen Liu Jin Wang, Yan Tan NIM Dr. JinTao Zhang Thank You for Attention! Summary  CRDS allows DBT measurement at lower pressures in near-IR;  Laser-locked CRDS allows spectral scan with high precision;  RD cell thermo-stabilized to  Statistical uncertainty <10 ppm (in line width) is feasible. To be improved  A new RD cell thermo-stabilized at K;  Laser with a line-width of 0.1kHz;  More accurate (and sophisticated) line profile model……