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Fusakazu Matsushima Department of Physics, University of Toyama, Japan

Generation of c oherent t erahertz radiation based on CO 2 laser mixing and its application to molecular spectroscopy of interstellar speci e s. Fusakazu Matsushima Department of Physics, University of Toyama, Japan. KAGRA face to face meeting, , Kashiwa, Ju ly 31 , 2012.

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Fusakazu Matsushima Department of Physics, University of Toyama, Japan

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  1. Generation of coherent terahertz radiationbased on CO2 laser mixing and itsapplication to molecular spectroscopy of interstellar species Fusakazu Matsushima Department of Physics, University of Toyama, Japan KAGRA face to face meeting,, Kashiwa, July31, 2012

  2. Univ. of Toyama and KAGRA Group Joint workshop July 7, 2012 in Toyama Many staffs in the faculties of science and engineering have much interest in KAGRA project. Now organizing researcher groups in Toyama U.. Coming Soon !!

  3. Microwave Physics Lab. Control of motion of molecules using Microwave → ultracold molecule → fundamental physics electric dipole moment of electron time evolution of fundamental constants Spectroscopy of interstellar molecules Laser Physics Lab. Atoms/molecules in liq. He Generation / selection of cold molecules Terahertz spectroscopy of molecules ←

  4. in my talk 1. Importance of the precise measurements in the far-infrared (terahertz) region 2. TuFIR spectrometer (CO2 laser difference frequency) 2-1. Principle 2-2. Application to molecules HeH+, OH-, H2D+, H2O (vibrational excited state)

  5. 1. Importance of the precise measurements in the far-infrared (terahertz) region

  6. Terahertz spectroscopy Wide scan spectrograph. for: Biological substance Non-destructive inspection High resolution spectroscopy Guanine frequency

  7. Terahertz spectroscopy • Target of the high precision / high resolution spectroscopy of moledules in the THz region • Rotational spectra of light molecules • 2 or 3 atomic molecules including hydrogen • 　 ex. water,　H2D+ •  ●astronomy, • ●remote sensing of atmosphere • ●"test stone" for newly proposed theories • Vib. Spectra of molecules with internal rotation • ex. methanol • 　　 Spectra with large amplitude vibration, inversion ex. Chain molecule • Vib. Rot spectra of molecular clusters • H2O, CO, N2　．．． • ●interface of gas phase and condenced phase

  8. International projects are in progress! Herschel Satelite 3.5m telescope, 2008 launch,57－670μm ALMA (Atacama Large Millimeter/submillimeter Array) 30GHz to 950GHz operation about 50 years from 2012 SOFIA (Stratospheric Observatory for Infrared Astronomy) 2.5m telescope on air craft (B747)from 2007 8 hours per mission, 120 mission per year, operate 20 years colaboration of the US (80%) and Germany (20%) 　　１－６００μm, Hot Water, Carbon Chemistry weeds CH3OH (CH3 internal rotation) Freq. Table up to 1THz HCOOCH3(CH3 int. rot.)Table up to 1.67THz, need for precision CH3OCH3 (two int. rot.) Table up to 2.17THz, need for precision CH3CH2CN (heavy mol.) Table up to 3.39THz, need for precision SO2 (heavy mol.) flowers H2O, O2, CO, ionic species Accuracy needed：better than １００ｋＨｚ. Want for data of vib. excited state.

  9. 2.TuFIR spectrometer (CO2 laser difference frequency) 2-1. Principle 2-2. Application to molecules (mainly molecular ions) HeH+, OH-, H2D+ H2O (vibrational excited state)

  10. THz sources gyrotron solid state gas laser ｍW multiplier Photo mixer μW TuFIR 0.3 ｎW from Matsui

  11. TuFIR spectrometer FIR=|I - II|±MW

  12. CO2 laser lines 9P 9R 10P 10R output power angle of grating

  13. difference freq. of two CO2 lasers upper or lower sideband Fourier transform spectrometer TuFIR

  14. MIM diode roof top mirror base whisker FIR micro wave CO2 laser

  15. MIM diode as detector / mixer Chain for the measurement of CO2 laser frequency MIM diode whisker Standard: Cs atomic clock

  16. TuFIR spectrometer FIR=|I - II|±MW

  17. Stabilization of the CO2 laser frequency 4.3m fluorescence CO2 fluorescence cell 1st derivative • Accuracy of stabilization • Accuracy of one CO2 laser 25kHz • Accuracy of difference freq. 36 kHz Laser frequency (cavity length)

  18. Data points are fitted with a theoretical curve (Voigt profile)  determine the center frequency

  19. Fig.1 TuFIR分光計 frequency range: up to 6THz precision of the source: about 30 kHz power: several tens to several hundreds nW F1 F2 F Fmw

  20. Molecules and ions measured with TuFIR spectrometer in Toyama (1) neutral molecules , radicals LiH, KH, １８OH, NH H2O (including isotopes, vibrationally excited state) (2) molecules with internal rotation CH3OH (3) cation protonated rare gas atoms (HeH+，NeH+， ArH+， KrH+， XeH+ ，including their isotopic species) H2D+ (4) anion OH- ，OD-

  21. Fig.1 TuFIR分光計 ion Configuration for detecting ionic species Velocity modulation: detects ions only

  22. HeH+

  23. HeH+ HeH+J=10 The lowest frequency rotational line 2010.1839 (2) GHz

  24. HeH+ HeH+Rotational Transition transition frequency obs-calc 4HeH+ J=10 2010183.873 (202) 0.108 J=21 4008733.084 (194) -0.148 4HeD+ J=21 2434626.571 (143) 0.077 J=32 3641427.274 (384) -0.210 J=43 4835691.417 (166) 0.039 3HeH+ J=10 2139522.472 (300) -0.213 J=21 4265839.060 (300) 0.330 3HeD+ J=21 2696099.975 (255) -0.021 J=32 4031223.001 (511) -0.650

  25. HeH+ Dunham coefficient Ykl EvJ = ΣYkl(v+1/2 )k[J(J+1)]l ( a set of coefficientsYkl for each isotope) To calculate all the isotopes with a set of coefficients Ukl Ykl　＝　μ-(k/2+l)Ukl Reduced mass μis not enough to fit all the isotopes. Ykl　＝　μ-(k/2+l)Ukl [1+meΔHekl/MHe + meΔHkl/MH] Correction terms usingΔvalues are necessary. Breakdown of Born-Oppenheimer approximation.

  26. HeH+ Delta coefficients included for HeH+ (v+ 1/2)k[J(J+1)]l

  27. OH- intensity(arb. units) 3363550.541frequency （MHz） 　　3363658.541 transition frequency (MHz) J=43 4478174.516 (387) J=32 3363607.066 (238) J=21 2244776.819 (240) J=10 1123100.985 (324)

  28. OD- J=2←1 J=3←2 Intensity (arb.units) Intensity (arb.units) D2O/O2=54.5/5Pa,AC1.2kHz,1.1A,4.8kV,Scan6回, エタノール冷却2℃,湿度60%,FIR200mV(≒100nW) ND3/O2=35/10Pa,AC1.2kHz,1.0A,5.6kV,Scan3回, 水冷,湿度29%,FIR140mV(≒70nW) Fit 1196791.042(0.486)MHz J=5←4 J=6←5 J=8←7 Intensity (arb.units) Intensity (arb.units) Intensity (arb.units) ND3/O2=35/10Pa,AC1.2kHz,1.0A,5.6kV,Scan3回, 水冷,湿度26%,FIR160mV(≒80nW) D2O/O2=23.5/5Pa,AC1.2kHz,1.2A,4.5kV,Scan3回, 水冷（溜め置き）,湿度60%,FIR150mV(≒75nW) ND3/O2=35/10Pa,AC1.2kHz,1.0A,5.6kV,Scan3回, 水冷,湿度24%,FIR40mV(≒20nW)

  29. OH-, OD-

  30. Evolution of interstellar molecules

  31. H2D+ typical trace of H2D+ 211 110

  32. H2D+

  33. H2O Rotational spectra of water in the Sun spectra 1995L. Wallace et al. “Water on the Sun”, Science, vol.268, pp.1155-1158, May 1995 Spectroscopy in the laboratory Flame sample Emission from discharge cell IR, FIR Fourier transform

  34. H2O Spectra near the Sun spot(L. Wallace 1995) ＊lines of water (Even the rotational lines in the v=0 state, high J lines cannot be calculated nor identified.)

  35. H2O Normal modes of water molecule

  36. 423414 line in the (1,1,0) vibrational state H2O Frequency (MHz) Energy of the 414 level: 5457.4 cm-1

  37. END

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