2 C DANIEL WITSCH VOLKER LUTTER GUIDO W FUCHS THOMAS GIESEN Institute of Physics University of Kassel Germany JÜRGEN GAUSS Institut für Physikalische Chemie Universität Mainz Germany ID: 634009
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Slide1
INFRARED SPECTROSCOPY OF DISILICON-CARBIDE, Si2C
DANIEL WITSCH, VOLKER LUTTER, GUIDO W. FUCHS, THOMAS GIESENInstitute of Physics, University of Kassel, GermanyJÜRGEN GAUSS,Institut für Physikalische Chemie, Universität Mainz, Germany .
Talk WA07
72
nd
Meeting ISMS June 2017
Champaign-Urbana, IllinoisSlide2
MOTIVATION
Astrophysics: SinCm molecules are building blocks of interstellar dust grainsRadioastronomical detection of
SiC
, SiC2, Si2C, c-SiC3, SiC4 in shells of late-type star IRC+10216ALMA revealed many U-lines in the dust forming region of IRC+10216TEXES and EXES/SOFIA new high resolution instruments for the mid-IRPhysical Chemistry:Vibrations, structures, chemical bonds of isovalent species SinC3-n, n ≤ 3
NEED OF MID-IR LABORATORY DATA Slide3
M.C. McCarthy et al., J. Chem. Phys. Lett. 6
, 2107 (2015)Microwave Spectra and Equilibrium Structure of Disilicon Carbide
1.69272(2) Å
114.871(3)°
Discovery of Si2C with 30m-IRAM in IRC+10216J. Cernicharo, M.C. McCarthy, C.A. Gottlieb et al., ApJ. Lett. 806, L3 (2015)
Ground State Vibrational Structure of Si
2
C:
Dispersed Fluorescence Spectroscopy at 390 nm
N.J. Reilly et. al.,
J.Phys.Chem
.
142
, 231101 (2015)
Electronic transitions of jet-cooled Silicon Carbides
Si
2
C
SiC
2
M. Steglich, J. P. Maier,
ApJ
801
, 119 (2015) Slide4
J.D.
Presilla-Marquez, W.R.M. Graham, J. Chem. Phys. 95, 5612 (1991)
Fourier transform vibrational spectroscopy of Si
2
C in solid ArInfrared Fundamental Modes and Relative Intensities Obs. a)
Ar Matrix
Theor. b)
This
c)
work
anharm
contr
.
c)
n
1
(a
1
)
839.5
808
838.0
-17.25
0.07
0.07
0.084
n
2
(a
1
)
(172)
131
142.7
-7.79
0.01
0.004
n
3
(b
2
)
1188.41223 1206.6-15.941.001.001.000
a) J.D. Presilla-Marquez, W.R.M. Graham, JCP 95, 5612 (1991)b) C. M. L. Rittby, JCP 95, 5609 (1991) MBPT2/6·311G(2d)c) CCSD(T)/cc-pCVQZ
INFRARED SPECTROSCOPY OF Si2C
(a
1
)
(a1)
(b
2
)Slide5
Infrared
Supersonic Jet SpectrometerSlide6Slide7Slide8Slide9
Si
2C ab initioA [MHz]B [MHz]C [MHz]Be
61361.1
4447.3
4146.7 Be-B0-2124.5 41.4 36.7BO63485.64405.9 4110.0 alpha-3737.8 68.1 43.9B1 (n3)59747.84474.0 4153.9n3 [cm-1]1206.6
Geometry: CCSD(T)/basis-set
limit+fc-CCSDT/TZ+fc-CCSDTQ/DZ+core/5ZVibration-rotation-constants and frequencies: CCSD(T)/cc-
pCVQZSlide10
Extended
Spectral RangeSlide11
Rotational
Diagram of Si2C Absorption Lines measured in a Supersonic Jet Expansion
J.
Cernicharo
, M.C. McCarthy, C.A. Gottlieb et al., ApJ. Lett. 806, L3 (2015)Rotational Diagram of Si2C Emission Lines measured in IRC+10216NJ /N(2J+1)Slide12
n3 (b2) Asymmetric Stretching Mode of Si2C at 1202 cm-1
Measured and Calculated Spectrum from best Fit Analysis Slide13
Pertubation
of Ka´´=2 levels by Coriolis Interaction
Coriolis
interaction
term ξC =0.01936(26) cm-1*
* N.J. Reilly et. al.,
J.Phys.Chem. 142, 231101 (2015)Slide14
Pure
Rotational Transitions up to 360 GHz Slide15
RESULTS Slide16
CONCLUSIONS
First Infrared gas-phase spectrum of Si2CExperimental results are in very good agreement with ab initio calculations
Precise
IR-
data for astronomical observations are now availableTHANK YOU FOR YOUR ATTENTION !