1. Vibrational energies for acrylonitrile from
66th OSU International Symposium on Molecular Spectroscopy MH09
Vibrational energies for acrylonitrile from
mm-wave to THz rotational spectra
Zbigniew Kisiel,a Lech Pszczółkowski,a
Brian J.Drouin,b Carolyn S.Brauer,b Shanshan Yu,b John C.Pearson,b
Ivan R.Medvedev,c Sarah Fortman,d Christopher Neesed
aInstitute of Physics, Polish Academy of Sciences, Warszawa, Poland
bJet Propulsion Laboratory, California Institute of Technology,
4800 Oak Grove Drive, Pasadena, CA
cDepartment of Physics, Wright State University, Dayton, OH 45435
dDepartment of Physics, The Ohio State University, Columbus, OH 43210

2. Fermi + c-axis Coriolis: DE = 228.29991(2) cm-1
The lowest vibrational states in acrylonitrile:
Kisiel, Pszczolkowski, Drouin, Brauer, Yu, Pearson,
J.Mol.Spectrosc. 258, 26 (2009)
Fermi + c-axis Coriolis:
DE = (2) cm-1
Only DE + one Coriolis (Fab) + three Fermi (WK, WJK, WKK ) interaction constants were necessary

3. Principal perturbations identified in aR-type g.s. transitions:
Differences relative to effective single state fits are plotted.
g.s. lines
11 = 1 lines
Broadband coverage possible well into the THz region with single scans reaching frequency spans of 100 GHz.
Ka = 6
Ka = 4

4. Ka = 10 Isotopic confirmation of the gs  n11 coupling model:
calc = CCSD(T)  6-31G(d,p)
H2C=CDCN
Ka = 10
Krasnicki, Kisiel, Drouin, Pearson, J.Mol.Struct. (2011), in press.

5. First set of spectra measured with the cascaded frequency multiplication spectrometer at jpl:
Drouin, Mailwald, Pearson, Rev.Sci.Instr. 76, (2005)
Broadband coverage possible well into the THz region with single scans reaching frequency spans of 100 GHz.

6. TOTAL COVERAGE = 1098 GHz The recorded spectra:
Praha2008
The recorded spectra:
Spectra were recorded at JPL and OSU using cascaded harmonic generation techniques and were merged into a single file
TOTAL COVERAGE
= 1098 GHz
spectra/GHz span/GHz

7. perturbation behaviour
Analysis tools: AABS package + SPFIT/SPCAT:
Praha2008
Loomis-Wood display
option T for plotting
perturbation behaviour

8. The strong n11  n15 Coriolis coupling dilemma:
A /MHz effective 2Aza gs
v11 =
v15 =
za11,15 = 0.625
But there is also coupling about the b-axis:
zb11,15 = 0.165
while similar 2Bzb behaviour is NOT observed
v15 =1 gs v11 =1
= =3
Cazzoli+Kisiel, J.Mol.Spectrosc 130, 303 (1988)

9. Selective perturbations for n11  n15 coupling :
as manifested in aR-type transition at high-J values
Ka = 4
Ka = 9
Ka = 5
v15 = 1
Ka = 11
Ka = 14
Ka = 3
J’’max = 55
533 GHz
v11 = 1
J’’max = 93
 885 GHz

10. bQ-branch for v11=1, Ka = 14  13 :
J = 54+55
J = 56+57
Obs.
Calc.

11. Matching bQ-branch for v15=1, Ka= 12  11 :
…but lines in this band are not yet well fitted since
the Ka= 12 levels of v15=1 couple with the Ka= 8 levels of v11=2
J = 54+55
J = 57
J = 56
Obs.
Calc.

12. Key results from fit of gs  n11  n15 coupling :
A /MHz (60) (15) (32)
B /MHz (50) (11) (19)
C /MHz (52) (10) (17)
DJ /kHz (16) (33) (70)
DJK /kHz (27) (25) (29)
DK /kHz (12) (29) (84)
dJ /kHz (38) (13) (31)
dK /kHz (18) (38) (17)
DE /MHz (46) (50)
A total of lines fitted at srms=1.37
Same interaction constants (4 Fermi+1 Coriolis) for the gs  n11 interaction as in the JMS2009 paper
A total of four a- and b-axis Coriolis constants for the n11  n15 interaction

13. (v11 = 1, v15 = 1) v10 = 1 Dyad near 570 cm-1: n10  n11 n15 coupling
The interaction is a- and b-axis Coriolis resonance and in aR-type transitions is maximized at moderate values of J (and visible for very low Ka)
Ka = 3 Ka+Kc=J+1
Ka = 3 Ka+Kc=J
(v11 = 1,
v15 = 1)
Ka = 2 Ka+Kc=J+1
Ka = 2 Ka+Kc=J
J’’max = 46
 450 GHz
J’’max = 30
 295 GHz
v10 = 1

14. Key results from fit of n10  n11 n15 coupling :
lower state upper state
A /MHz (52) (12) fitted lines = 1650
B /MHz (77) (77) rms = 1.4
C /MHz (62) (68)
DJ /kHz (20) (19)
DJK /kHz (84) (10)
DK /kHz (18) (55)
dJ /kHz (12) (12)
dK /kHz (84) (14)
DE /MHz (51) + 7 other Ga,Gb based
interaction constants
LOWER = n UPPER = n11,n15
expt calc* expt calc*
Av-A0 /MHz
Bv-B0 /MHz
Cv-C0 /MHz
*CCSD(T)/6-31G(d,p)

15. Vibrational energies from perturbations:
Two state fit:
E(v11 =1, v15 =1) - E(v10 =1)
= (2) cm-1
Three state fit:
this work FIR*
v11 = (2) (18)
v15 = (2) (9)
* Cole+Green, J.Mol.Spectrosc.
48, 246 (1973)

16. Praha2008
SUMMARY:
The coverage of the room temperature rotational spectrum of acrylonitrile has been increased in extent to a total of 1098 GHz and in the upper frequency limit to 1.9 THz
Several specific n11  n15 perturbations have been identified and fitted in the interaction scheme gs  n11  n15
The precise values of E11= (2) cm-1 and E15 = (2) cm-1 are consistent with those from gas-phase FIR determination
For the two closely spaced states near 570 cm-1 a successful n10  n11 n15 coupled fit was achieved, and the states were assigned unambiguously on the basis of Bv-B0 values calculated from the ab initio anharmonic force field
Identification of further specific interactions (in particular those affecting 2n11 ) is in progress in order to incorporate the g.s. and the five lowest vibrational states into a single coupled fit