1. COMPREHENSIVE ANALYSIS OF INTERSTELLAR
Grupo de Espectroscopia Molecular, Lab. De Espectroscopia y Bioespectroscopia, Edificio Quifima, Unidad Asociada CSIC,
Universidad de Valladolid, Valladolid, Spain
COMPREHENSIVE ANALYSIS OF INTERSTELLAR
Iso-PROPYL CYANIDE UP TO 480 GHz
Lucie Kolesniková, Elena R. Alonso, Carlos Cabezas, Santiago Mata, José L. Alonso
International Symposium on Molecular Spectroscopy, June 20  24, 2016
Champaign-Urbana, Illinois, USA

2. Research in our group is devoted to :
*Rotational Spectra of Molecules of Astrophysical Interest
The combination of Lab. Data and Radioastronomy provides a power
capability for the detection and conclusive identification of molecular
species in the ISM
Frequency Domain
Stark Modulation MW: GHz
Millimeter and Submillimeterwave : GHz
*Conformation and Structure of Biomolecules.
Rotational studies of solid biomolecules by FTMW spectroscopy in a
supersonic expansion combined with laser ablation techniques of
vaporization.
Time Domain
MB-FTMW: GHz
LA-MB-FTMW : GHz
LA-MB-FTMW : 4-26 GHz
CP-FTMW: GHz

3. Introduction and motivation
Branched alkyl molecule detected in the hot core of Sgr B2(N)a
Its detection based in the identification of about 50 ground state
rotational transitions found between 84 and 111 GHz (ALMA survey)
a A. Belloche, R. T. Garrod, H. S. P. Müller, and K. M. Menten: Science 345 (2014) 1584.

4. Previous rotational studies
Authors
Year
Freq. range
Description
G. E. Herbericha
1967
5  30 GHz
Stark spectroscopy: GS, rotational and 14N nuclear quadrupole coupling constants
J. R. Durig  Y. S. Lib
1974
26  40 GHz
Stark spectroscopy: GS and three excited vibrational states, dipole moment, structural parameters
H.S.P. Müller et al.c
2011
6  20 GHz
FTMW spectroscopy: accurate 14N nuclear quadrupole coupling constants
37  600 GHz
FM + Stark spectroscopy: accurate GS rotational and cent. distortion constants, dipole moment revised
no excited vibrational states in the MMW region, no 13C species
a H. S. P. Müller et. al: J. Mol. Spectrosc. 367 (2011) 100; b J. R. Durig and Y. S. Li: J. Mol. Struct. 21 (1974) 289; c G. E. Herberich: Z. Naturforschg. A 22 (1967) 543.

5. Experimental procedure
Stark-modulation spectra
Ab initio
calculations
GS and excited vibrational states assignments : preliminary set of spectroscopic contants
mm and subm-mw spectra
Assignments
Loomis-Wood plot technique
Global Fit
(A, B, C, DJ, DJK, DK, …)

6. Experimental procedure
Stark-modulation spectra
Ab initio
calculations
GS and excited vibrational states assignments : preliminary set of spectroscopic contants
Line survey
mm and subm-mw spectra
Detection?
Assignments
Loomis-Wood plot technique
Synthesized spectrum
MADEX code
Global Fit
(A, B, C, DJ, DJK, DK, …)

7. 1. Stark-modulation rotational spectra
MW Source
Stark Cell
Detector
(50  75 GHz) n t I
Stark Modulation n

8. Stark-modulation rotational spectra
(300 Vcm1)
ma = (50) D
G.S.

9. Stark-modulation rotational spectra
ma = (50) D
G.S.
Vibrational satellite pattern

10. Stark-modulation rotational spectra
Trans-propenal
Pure rotational spectra in the ground
state and vibrational excited states
Ground State

11. Vibrational satellite analysis
Ab initio calculations (MP2/ G(d,p), B3LYP/ G(d,p),…)
vibrational frequencies
(14 A’  10 A’’ normal modes)
predictions of rotation-vibration coefficients
five normal modes below 400 cm1
n30
n17
n29
190 cm1, bending (A’’)
219 cm1, torsion (A’)
 223 cm1, torsion (A’’)
n16
n15
353 cm1, scissoring (A’)
283 cm1, bending (A’)

12. Experimental procedure
Stark-modulation spectra
Ab initio
calculations
GS and excited vibrational states assignments : preliminary set of spectroscopic contants
mm and subm-mw spectra
Assignments
Loomis-Wood plot technique
Global Fit
(A, B, C, DJ, DJK, DK, …)

13. Millimeter and Submillimeter Wave Spectrometer
Double pass configuration (50 – 170 GHz)

14. Millimeter and Submillimeter Wave Spectrometer
Double pass configuration (50 – 170 GHz)

15. Millimeter and Submillimeter Wave Spectrometer
Double pass configuration (50 – 170 GHz)

16. Millimeter and Submillimeter Wave Spectrometer
Double pass configuration (50 – 170 GHz)

17. Millimeter and Submillimeter Wave Spectrometer
Single pass configuration (170 – 1000 GHz)

18. Millimeter and Submillimeter Wave Spectrometer
Single pass configuration (170 – 1000 GHz)

19. Millimeter and Submillimeter Wave Spectrometer
Single pass configuration (170 – 1000 GHz)
80 – 480 GHz
room temperature
12 mbar

20. Iso-propyl cyanide: MMW + Stark spectrum
Loomis-Wood type display facilities of the AABS package of Kisiel
ncent(MHz)
Dn (MHz)

21. Iso-propyl cyanide: MMW + Stark spectrum
Loomis-Wood type display facilities of the AABS package of Kisiel
ncent(MHz)
FM spectra
(80  480 GHz)
Stark spectra
(50  75 GHz)
Dn (MHz)

22. Iso-propyl cyanide: MMW + Stark spectrum
ncent(MHz)
G.S.
Dn (MHz)

23. Iso-propyl cyanide: MMW + Stark spectrum
ncent(MHz)
v30 = 1
v15 = 1
G.S. ?
v16 = 1
v30 = 2 ?
v29 = 1
v17 = 1 ?
Dn (MHz)

24. Iso-propyl cyanide: MMW + Stark spectrum
G.S.
ve = 1
vd = 1
va = 1
vd = 2 ?
ncent(MHz)
vg = 1
v30 = 1
v17 = 1
v16 = 1
v15 = 1
v30 = 2
v29 = 1
v30 = 3
Dn (MHz)

25. Iso-propyl cyanide: Analysis
S-reduced Hamiltonian (Ir-representation) up to the sixth order

26. Iso-propyl cyanide: Analysis
S-reduced Hamiltonian (Ir-representation) up to the sixth order
Perturbations observed in several excited vibrational states
e.g.
n17
(A’)
n29
(A’’)

27. Iso-propyl cyanide: Analysis
S-reduced Hamiltonian (Ir-representation) up to the sixth order
Perturbations observed in several excited vibrational states
v17 = 1
Ka = 2, 3
e.g.
Ka = 1, 2
(nv  nGS) / (J’’ + 1) (MHz)
Ka = 1, 2
Ka = 0, 1
v29 = 1
n17
(A’)
n29
(A’’)
J’’ + 1

28. Conclusions and future plan
Stark and MMW spectra of iso-propyl cyanide measured and analyzed between 26 and 480 GHz
10 excited vibrational states identified (and more line sequences observed)
Perturbations between individual states observed
interactions planned to be analyzed
13C species observed in the natural abundance
analysis in progress

29. Molecular Astrophysics
Acknowledgements
CSD
Molecular Astrophysics
Grants CTQ P
and AYA
Grant VA070A08
(FP/ ) / ERC-2013-SyG
Grant No
…and all the members of