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High-J rotational lines of HCO + and its isotopologues measured by using Evenson-type tunable FIR spectrometer R. Oishi, T. Miyamoto, M. Suzuki, Y. Moriwaki, F. Matsushima Department of Physics, University of Toyama, Japan T. Amano Department of Chemistry, University of Waterloo, Canada
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Background /Spectroscopy of HCO + Rotational transitions 1970 Buhl and Snyder: Discovery of “X-ogen” 1975 Woods et al: Laboratory identification of “X-ogen” HCO +. 2006 Buffa et al 2007 Tinti et al 2012 Cazzoli et al Extension to higher-J lines, up to J=17 - 16. Vibration-rotation transitions (IR) 1983 Gudeman et al: ν 1 band ( R(0) to R(18) ) Amano: ν 1 band (P(10) to R(9) ). 2007 Verbraak et al: CRD with with cw-OPO 2013 Siller et al: Lamb dip with cw-OPO and frequency comb → “Indirect” measurements of the rotational transitions up to J ≤ 10 In this investigation: Extended precise measurements of the rotational lines to higher-J
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TuFIR spectrometer at University of Toyama FIR =| I - II |± MW
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Extended negative glow discharge cell Pressure H 2 : 0.3Pa, CO: 0.3Pa, Ar: 2.4Pa Discharge current: 10 〜 20mA, voltage 1 〜 3.5kV Cell: Diameter: 32mm, length 1.5m
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汚れた内管の写真 Replaceable double jacketed discharge tube with liquid nitrogen cooling capability Two straight glass tubing with different diameters are assembled with plastic flange and heat-shrink tubing → easy replacement of soiled inner tubing
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980636.508 (36) MHz 1958629.025 (63) MHz Measurement of HCO + rotational lines J=11<-10 J=22<-21
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1 0 89188.5247 -1.5 2 1 178375.0563 -8.1 3 2 267557.619 -8 4 3 356734.2230 -1.7 5 4 445902.8721 0.8 6 5 535061.5810 2.1 7 6 624208.3606 -0.1 8 7 713341.2278 -1.9 9 8 802458.1995 -0.5 10 9 891557.2903 4.7 11 10 980636.510 9 12 11 1069693.850 -12 13 12 1158727.429 45 14 13 1247735.112 29 15 14 1336714.999 23 16 15 1425665.082 3 17 16 1514583.352 -57 18 17 1603468.010 25 19 18 1692316.839 16 20 19 1781127.946 6 22 21 1958629.075 -7 Measured Transition Frequencies for HCO + J’ J obs/MHz (o-c)/kHz J’ J obs/MHz (o-c)/kHz Cazzoli et al, ApJS, 203, 11 ( 2012) Sastry et al, JCP, 75, 4169 (1981)
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B /MHz 44594.428788( 157) 44594.42895(27) D /kHz 82.8370( 22) 82.8412(60) H /Hz 0.1011( 108) 0.137(46) L /mHz -0.0359( 145) -0.118(91) H = BJ(J+1) –D[J(J+1)] 2 + H[J(J+1)] 3 +L[J(J+1)] 4 Molecular constants for HCO + Present Cazzoli et al a a G. Cazzoli, L. Cludi, G. Buffa, C. Puzzarini, ApJS. 203, 11 (2012)
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1007941.236 (36) MHz 1797504.091 (58) MHz Measurement of DCO + rotational lines J=14<-13 J=25<-24
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1 0 0 1 72039.2413 -0.3 1 2 0 1 72039.3028 -1.3 1 1 0 1 72039.3504 -0.8 2 1 144077.2890 2.5 3 2 216112.5822 0.5 4 3 288143.8583 -1.1 5 4 360169.7783 -2.4 6 5 432189.0052 -1.8 7 6 504200.1999 -0.1 8 7 576202.0239 2.2 9 8 648193.1357 1.3 10 9 720172.2024 1.7 11 10 792137.8811 -2.8 12 11 864088.890 47 13 12 936023.7532 -1.4 14 13 1007941.254 -16 15 14 1079840.081 24 16 15 1151718.735 -45 17 16 1223576.080 -24 18 17 1295410.668 -24 19 18 1367221.232 25 20 19 1439006.283 -30 21 20 1510764.676 5 22 21 1582494.967 24 23 22 1654195.707 -79 24 23 1725866.004 147 25 24 1797503.697 -118 Measured Transition Frequencies for DCO + J’ F’ J F obs/MHz (o-c)/kHz J’ J obs/MHz (o-c)/kHz Caselli and Dore, A&A, 433, 1145 (2005) Lattanzi et al, ApJ, 662, 771 (2007)
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B /MHz 36019.76805(34) 36019.76765(14) D /kHz 55.8029(34) 55.7960(22) H /Hz.0920( 96) 0.054(11) L /mHz -.0469(82) c /kHz -1.34(233) -1.59(78) eQq /kHz 148.0(101) 147.8(35) Molecular Constants for DCO+ Present Caselli and Dore a a P. Caselli and L. Dore, A&A, 433, 1145 (2005)
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ln I/(J+1) E low /MHz Rotational Temperature ≈ 120K Rotational Temperature To reach higher-J lines: Higher cell temperature Decrease the density of ions
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N 2 H + J=5←4 temperature dependence, sub-mm spectrometer -200C (liq. N2 temp) -100 -85 -65 -30 -15 -5 +20 (room temp.)
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Summary HCO +,DCO + : Frequencies of rotational lines with high J-quantum numbers were measured precisely using a TuFIR spectrometer. Rotational parameters were improved. Measutements of 13 C isotopologues: H 13 CO + and D 13 CO + are in progress.
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Acknowledgment Grant-in-Aid from the Ministry of Education, Culture, Sports, Science and Technology of Japan Natural Science and Engineering Research Council of Canada (NSERC) Department of Chemistry, University of Waterloo
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TuFIR (CO 2 laser difference frequency) How to obtain the tunability using wave guide CO 2 laserusing MW source tunability ~ 100MHz need many combinations tunability ~ 20GHz power: 2 nd > 3 rd
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Simulation of the absorption intensity I=abs.int. μ=dipole moment B=rotational constant 1.201492049(cm -1 ) h=Plank constant k=Boltzman constant 0.69501(cm -1 /deg) J 77K 120K 300K Abs.int (arb.units)
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