Transcript 2007_Columbus_HCO+.ppt

Submillimeter-wave Observation of
HCO+ and DCO+
in the Excited Vibrational States
T. Hirao
Shanshan Yu and T. Amano
Astronomical detection of HCO+
 Buhl et al. (1970): X-ogen line (89.190 GHz)
…
 Snyder et al. (1997): giant molecular clouds such as Orion
 Girart et al. (2000): molecular outflows
 Qi et al. (2003): the envelope around a t-tauri star
 Sáchez et al. (2004): protoplanetary nebula
 Purcell et al. (2006): massive star forming regions
Laboratory spectroscopy of HCO+
 Ground state:
HCO+(J = 12-11, 1.1 THz ); DCO+: (J =11-10, 0.8 THz )
R.C. Woods et al. (1975, 1981), K.V.L.N. Sastry et al. (1981), M. Bogey et
al. (1981), F.C. van den Heuvel et al. (1982), P. Caselli et al. (2005)
 Excited vibrational states:
HCO+: 100, 010, 001, 020 (below 450 GHz)
DCO+: 100, 010, 001, 011, 020, 030, 040 (below 450 GHz)
G.A. Blake et al. (1987), E. Hirota et al. (1988), L. Dore et al. (1996, 2003)
 Infrared spectroscopy:
HCO+: n1, n2 and n3, DCO+: n1 and n3
C.S. Gudeman et al. (1983), T. Amano (1983), P.B. Davies et al. (1984),
S.C. Foster et al. (1984), K. Kawaguchi et al. (1985,1986),
HCO+: 002-001, 011-010 [D.J. Liu et al. (1988)]
Laboratory spectroscopy of HCO+
 V. Lattanzi et al. (2007):
HCO+ and DCO+: 000 and 010 (up to 1.2 THz)
 C.F. Neese et al. (2007):
HCO+: 110-010, 120-020, 101-001, 111-011, 200-100, 102-002
Other motivations
 Hirota and Endo: Lowest three lines observed for (001),
(100), (0110) and 0200; but (0220) counterparts undetected;
(0110) lines show systematic deviations (hollow cathode
discharge)
Stark effect
 Dore et al.: Similar systematic deviations in (0110), (0220),
(0310), and (0420) states of DCO+ (extended negative glow
discharge)
Stark effect?
 No anomalies observed for submillimeter-wave lines of
symmetric top ions, CH3CNH+ and SD3+. ( the lines of K≠0
should have the first order Stark effect)
 The 0220, 0310 and 0420 rotational lines of HNC and HCN
observed without anomalies.
Pump
Electrode CO, H2, Ar
Coolant in
Submillimeter
radiation (BWOs)
InSb
detector
Coolant out
PC
Pre-Amp.
Solenoid
power supply
On-off modulation
Function
generator
Frequency
modulation
22.5 Hz
Ref. #2
Lock-in #2
Lock-in #1
30 kHz
Rf synthesizer
Ref. #1
• Frequency range: 270~860 GHz
• Extended negative glow discharge: ~10 mA, ~3kV; ~ 1 mTorr of H2/ D2;
~ 1 mTorr of CO; ~10 mTorr of Ar; LN2 cooling
HCO+ spectrum
DCO+ (010)
Endo et al.
DCO+ (020)
Emission lines in 0220
DCO+ (030)
l-doubling in DCO+ (0330)
l-doubling in DCO+ (0330)
μ•E
μ•E
DCO+ (040)
Conclusions
 Extensive measurements (up to 800 GHz) have been carried
out and improved parameters were obtained:
HCO+: 100, 010, 001, 002, 011, 020, 030, 040, 110, 031, 0201
DCO+: 100, 010, 001, 011, 020, 030, 040
 Some low-J DCO+ lines in (010) and (0420), which were
observed with systematic shifts in previous works, were
observed with no shifts in the present study.
 Induced emission lines observed in (0220), (0310) and (0420) ,
which indicates that in our case population inversion, instead
of Stark effects, is responsible for the non-observation of some
low-J lines.
 The stark effect was simulated for some lines in 0330 of DCO+,
and was found to be unable to explain the observed lines.
Acknowledgements
 Ministry of Education, Science, and Culture of Japan
 Japan Society for Promotion of Science (JSPS)
 National Institute for Communications Technology
(NICT), JEM/SMILES Project
 Natural Science and Engineering Research Council of
Canada (NSERC)
 University of Waterloo
l-doubling in (030)
f-level
e-level
J=11←10
ΔEl’ ~ 24.4 MHz
23.885 MHz
(obs)