ROTATIONAL SPECTRA OF UREA IN ITS GROUND
AND FIRST EXCITED VIBRATIONAL STATES
Jessica Thomas, Ivan Medvedev,
Department of Physics, Wright State University
Zbigniew Kisiel, ON2, Institute of Physics,
Polish Academy of Sciences, Warszawa Poland
PREVIOUS RESEARCH
Brown,R. D., Godfrey, P. D., and Stomey, J., The Microwave Spectrum of Urea. Journal of
Molecular Spectroscopy, 1975. 58, 445.
Kretschmer, U., D. Consalvo, A. Knaack, W. Schade, W. Stahl and H. Dreizler. The 14N
Quadrupole Hyperfine Structure in the Rotational Spectrum of Laser Vaporized Urea
Observed by Molecular Beam Fourier Transform Microwave Spectroscopy, Molecular
Physics. 1996. 1159-1168.
S. Kassi, D. Petitprez, and G. Wlodarczak. Microwave Spectrum of Isotopic Species of Urea,
Journal of Molecular Spectroscopy, 2004. 228, 293-297.
Inostroza, N. M.L. Senent. Large Amplitude Vibrations of Urea in Gas Phase, Chemical
Physics Letters, 2012. 524, 25-31.
H.-L. Kuo, et al. http://molspect.chemistry.ohio-state.edu/symposium_65/symposium
Jessica R. Thomas, Alyssa M. Fosnight, Ivan R. Medvedev. “Analysis of the Submillimeter
Rotational Spectra of Urea” (Columbus Ohio, 2013)
Remijan, A. J., Snyder, L.E, McGuire, B. A., et al Observational Results of a Multi-Telescope
Campaign in Search of Interstellar Urea. The Astrophysical Journal 2014 March 10
IS UREA OUT THERE?
•Urea has been found in samples of carbonaceous meteorites,
such as the Murchison meteorite
•Line frequencies believed to be that of urea have been
observed in the hot molecular core of Sgr. B2 (N-LMH) using
CARMA and IRAM.
•Urea and several other species has detected in the spectra
of NGC 7538 IRS9 protostellar ice using IR techniques
H.-L. Kuo, et al. http://molspect.chemistry.ohiostate.edu/symposium_65/symposium
Tentative identification of urea and formamide in ISO-SWS infrared spectra of interstellar
ices, (Raunier, et. all, 2004)
UREA THE MOLECULE
Molecular
Formula
CH4N2O
Molar Mass
60.06 g/mol
Density
1.32g/cm
Melting
point
133-135C
Dipole
moment
4.56 Debye
Oblate asymmetric top with
b-type transitions
Image: https://en.wikipedia.org/wiki/File:Urea_3D_ball.png
SP2
SP2
SP2
Gas
Inlet
OUR SYSTEM
Continuous Wave THz Spectrometer
VDI Diode
Multipliers
Virginia Diodes
Absorption Cell
2 m long by 4in
wide (14 L)
x24
Lock in
IF detector
IF
Computer
LO
Sideband
filter
Stepping
Synthesizer
Sweeping
Synthesizer
• Pressure controls
•Liquid helium controlled
InSb bolometer
Custom Built Microwave
Synthesizer
VDI
Receiver
Custom Built
VDI
Transmitter
Microwave
Synthesizer
Absorption Cell: length - 2 m ,
volume - 14 L
Absorption
Cell
PROCEDURES
Gas
Inlet
Lock in
Spfit programs
IF detector
IF
Computer
VDI
Receiver
x24
VDI
Transmitter
Absorption Cell: length - 2 m ,
volume - 14 L
LO
Sideband
filter
Stepping
Synthesizer
Sweeping
Synthesizer
Pickett, H.M., R.L. Poynter, E.A. Cohen, M.L.
Delitsky, J.C. Pearson, and H.S.P. Muller,
Submillimeter, Millimeter, and Microwave
Spectral Line Catalog. Journal of Quantitative
Spectroscopy and Radiative Transfer, 1998.
60(5): p. 883-890.
Igor Pro
•CAAARS
Medvedev, I.R., M. Winnewisser, B.P.
Winnewisser, F.C. De Lucia, and E. Herbst, The
use of CAAARS (Computer Aided Assignment of
Asymmetric Rotor Spectra) in the analysis of
rotational spectra. Journal of Molecular
Structure, 2005. 742(1-3): p. 229-236.
OUR SPECTRUM
Decomposition reaction:
NH2CONH2 + heat  NH4+NCO- HNCO + NH3
THE STATES OF UREA
DE= 50
cm-1
Ground State
1st Excited State
2nd Excited State
3rd Excited State
M.Inostroza, M.L.Senent,
Chem.Phys.Lett. 524, 25 (2012)
GROUND STATE
Parameter Current Value
1013 lines assigned with J
numbers ranging from 11 to 65
A / MHz
B / MHz
C / MHz
ΔJ / kHz
ΔJK / kHz
ΔK / kHz
δJ / kHz
δK / kHz
fJ /Hz
fJK /Hz
fKJ /Hz
fK /Hz
Avg. / kHz
rms /kHz
Previous Value Multi-Telescope
Campaign
11233.30401( 47) 11233.3161(87) 1233.3212(10)
10369.39589( 42) 10369.4074(88) 10369.3727(11)
5416.62848( 50) 5416.6392(86)
5416.6320(9)
10.77813( 59)
10.58(37)
5.5268(21)
21.03046(197)
20.982(53)
−5.2788(85)
10.97866(160)
10.80(29)
10.961(11)
0.218632(250)
.2208(43)
2.40056(79)
14.4951( 76)
14.6439(73)
3.9044(37)
0.015626(145)
0.118934(167)
0.265272(245)
0.161890(163)
3.029
47.957
FIRST VIBRATIONAL STATE
945 lines assigned with J
numbers ranging from 10 to 63
Parameter
Current Valuea
A / MHz
11208.96619( 51)
B / MHz
10361.07867( 47)
C / MHz
5419.07180( 53)
ΔJ / kHz
10.72516( 58)
ΔJK / kHz
20.88655(197)
ΔK / kHz
10.89549(197)
δJ / kHz
0.168029(248)
δK / kHz
14.5110(78)
fJ /Hz
0.015520(151)
fJK /Hz
0.114563(222)
fKJ /Hz
0.26252( 32)
fK /Hz
0.163275(202)
Avg. / kHz
3.993
rms /kHz
47.625
NUMERICS
Ground State
Parameter
A / MHz
B / MHz
C / MHz
2
Ia / amu A
2
Ib/ amu A
2
Ic/ amu A
Ia+ Ib- Ic
ҡ
11233.30401
10369.39589
5416.62848
45.00287712
48.75221328
93.32945796
0.425632439
0.702954681
Ground State
1st Excited State
Previous Values
11233.3161
10369.4074
5416.6392
45.00282868
48.75215916
93.32927325
0.425714597
0.702954551
Ia+ Ib- Ic= 4mHrH2 = Iα = 3.214376799
11208.96619
10361.07867
5419.0718
45.10059103
48.79134848
93.28737811
0.6045614
0.707114685
CONCLUSION
This experiment assigned the ground state and the first
vibrational state between 210 -270 and 300-500 GHz,
and refined the rotational constants that were
furnished by previous microwave studies.