20 June 200661 st International Symposium on Molecular SpectroscopyPetkie – TG03-p1 The Millimeter and Submillimeter-wave Spectrum of the 8 1 9 1, 6 1

20 June 200620 June 2006 6161stst International Symposium on Molecular Spectroscopy International Symposium on Molecular Spectroscopy Petkie – TG03-pPetkie – TG03-p11

The Millimeter and Submillimeter-wave Spectrum of the 8191, 6171, and 21 Vibrational States of Nitric

Acid

Douglas T. PetkieDepartment of Physics, Wright State University

Paul HelmingerDepartment of Physics, University of South Alabama

Ivan R. Medvedev, Atsuko Maeda, Frank C. De LuicaDepartment of Physics, Ohio State University

International Symposium on Molecular Spectroscopy61th Meeting

June 19-23, 2006The Ohio State University

Columbus, Ohio


Outline

• Introductory remarks and overview

• Experimental details and data

• Details of each state/analysis

– previous studies, current assignments and analyses

2 = 1

6 = 7 = 1 and 8 = 9 = 1

– Torsional splitting

• Summary


Nitric Acid Vibrational States

Review article “Recent progress in the analysis of HNO3 spectra” by A. Perrin, Spectrochimica Acta Part A 54 (1998) 375–393.


Nitric Acid Vibrational Levels

assignments and initial analyses

Published analyses

a = 1.98 D b = 0.88 D

a-type Ka = 0, 2 Kc = 1, 3

b-type Ka = 1, 3 Kc = 1, 3

N

O O

O

H

Current Focus

Current Focus


Interference fringes Spectrum

InSb detector 1

InSb detector 2

Ring cavity: L~15 m

Mylar beam splitter 1

Mylar beam splitter 2

High voltagepower supply

Slow wave structuresweeper

Aluminum cell: length 6 m; diameter 15 cm

Trigger channel /Triangular waveform channel

Sig

na

l ch

an

ne

l

BWO

Magnet

Lens

Filament voltagepower supply

Length ~60 cm

Steppermotor

Reference channel

Lens

Stainless steel rails

Path of microwaveradiation

Preamplifier

Fre

qu

en

cy

ro

ll-o

ffp

rea

mp

lifi

er

Referencegas cell

Glass rings used to suppress reflections

Data acquisition system

Computer

FAst Scan Submillimeter Spectroscopic Technique (FASSST) spectrometer

WI04:WI04: FAFAST ST SSCAN CAN SSUBMILLIMETER UBMILLIMETER SSPECTROSCOPIC PECTROSCOPIC TTECHNIQUE (FASSST). ECHNIQUE (FASSST).


FASSST Data• 118-375 GHz, Heated ~180 oC, Signal averaged data ~ time constant ~ 20 msec

• plus “legacy data” (78-118 GHz synthesizer and older FASSST data)


-800x103

-600

-400

-200

0

200

400

Sig

na

l/a.u

.

260x103

255250245240Frequency/GHz

R and Q Branches

FASSST Spectra

Simulation ofground state


4000

3000

2000

1000

0

-1000

-2000

106.6106.4106.2106.0105.8105.6x10

3

gs

32

Assignment Methodology

7080 78

106 GHz region

Frequency /GHz

Sig

nal/a

u


Relevant Studies of 2 = 1 2 High-resolution infrared studies (b-type transitions):

– Laser Diode:• C. H. Bair and P. Brockman, Appl. Opt. 18, 4152-4162 (1979)• A. G. Maki and J. S. Wells, J. Mol. Spectrosc. 82, 427-434 (1980)• A. Maki, J. Mol. Spectrosc. 127, 104-111 (1988)

– 15 MHz, 1680 – 1738 cm-1, J = 66, Ka = 35, Kc = 60– No perturbations:

» few low Ka do not fit: 1676-1683, 1731-1736 cm-1

– FTIR:• T.L. Tan, et al., J. Mol. Spectrosc. 155, 420-423 (1992)

– 15 MHz, J = 72, Ka = 45, Kc = 72– 1675-1684, 1730-1737 cm-1, Ka ≤ 7 (J~64)

» obs-calcmax = 245 MHz (0.0082 cm-1)» Severely overlapped, as with Maki» Excluded from analysis and not understood


2 = 1 Assignments and Spectra


R-Branch SummaryInfrared transitions obs-calc up to 245 MHz

R = Fitted TransitionRP = well predicted clear region, missing transitionRP? = well predicted but congested* = no spectra available


Q-Branch SummaryInfrared transitions obs-calc up to 245 MHz

Q = Fitted TransitionQP = well predicted clear region, missing transitionQP? = well predicted but congested* = no spectra available


2 = 1 Spectroscopic Parameters and Summary

• Starting point was Tan, et al. constant set

• Watson A-reduced Hamiltonian in the Ir representation

• 207 fitted transitions between

78-505 GHz• Maximum Quantum Numbers

J = 40, Ka = 19, Kc = 40

• 117 kHz rms deviation• Constants in fairly good

agreement with ir work• Possibility of perturbation• Spectral congestion


96

72

98

76

Infrared Laboratory Spectrum


Nitric Acid Vibrational Levels

assignments and initial analyses

Published analyses

a = 1.98 D b = 0.88 D

a-type Ka = 0, 2 Kc = 1, 3

b-type Ka = 1, 3 Kc = 1, 3

N

O O

O

H

Current Focus

Current Focus


Previous Studies for8 + 9 and 6 + 7

• A. G. Maki, J. Mol. Spectrosc. 136, 105–108 (1989).– Infrared Spectrum of the 1205 cm-1 Band of HNO3

• T. M. Goyette and F. C. De Lucia, J. Mol. Spectrosc. 139, 241–243 (1990).– The millimeter and Submillimeter Wave Spectrum of the 8 + 9 State of HNO3

• W. F. Wang, P. P. Ong, T. L. Tan, E. C. Looi, and H. H. Teo, J. Mol. Spectrosc. 183, 407–413 (1997).

– Infrared Analysis of the Anharmonic Resonance between 8 + 9 and the Dark State 6 + 7 of HNO3

• A. Perrin, J.-M. Flaud F. Keller, A. Goldman, R. D. Blatherwick, F. J. Murcray, and C. P. Rinsland, J. Mol. Spectrosc., 194, 113–123 (1999).

– Analysis of the 8 + 9 Band of HNO3, Line Positions and Intensities, and Resonances Involving the v6 = v7 = 1 Dark State


500x103

400

300

200

100

0

-100

-200

Sig

na

l/a.u

.

220.0x103

219.5219.0218.5218.0217.5217.0Frequency/GHz

8000

4000

0

-4000

6171 and 8191 Assignments and Spectra

Predicted SpectraX50 vertical scale

FASSST Spectra

6171 8191


15x103

10

5

0

-5

-10

Sig

na

l/a.u

.

218.04x103

218.02218.00217.98217.96217.94217.92217.90Frequency/GHz

6=7=1 Assignments and Spectra

R-Branch “Triplets”


Torsional Effects on the Spectrum

J+10,J+1

J+11,J+1

J+11,J+1

J+10,J+1

J0,J

J1,J

J1,J

J0,J

a-type b-type

R-Branch

o

0.6

0.4

0.2

0.0

-0.2

315.98315.96315.94315.92x10

3

b-type


Torsional Splitting SummaryState Observed

Splitting in MHz

9 2.34

5 35.43

9 50.80

7+9 12.26

6+9 22.76

7 Not resolved

8+9 3.35

6+7 1.48

9 1746.83

6 0.75

4 4.03

3 3.88

7+8 2.26

7191 Triplet

b ba

316 GHz region

40

20

0

-20

Sig

na

l (A

U)

315980315960315940315920Frequency (MHz)Frequency/MHz

Sig

nal/a

u


IAS Hamiltonian: 6171 and 8191 States• IAS (Internal Axis System) Hamiltonian

– SPFIT, SPCAT (Pickett /JPL)

• IR representation in the A-reduction (z = a, x = b, y = c)

• Interaction terms– Fermi and c-type Coriolis terms

termsaldistortionorderhigher

KEJJJJDCJBJAJH abbaabcbavv

)cos(222

abbaab

cbaKJovv

JJJJC

JJFJFJFFH 2222 2

2aK

framerotor

rotor

II

I

J+10,J+1

J+11,J+1J+11,J+1

J0,J

J1,JJ1,J

J0,J

a-type b-type

R-Branch

ob-type


• General

– H. M. Pickett, J. Chem. Phys. 107, 6732 (2001)

– Hougen, J. Mol. Spectrosc. 114, 395 (1985)

• HNO3

– A. Perrin, J. Orphal, J.-M. Flaud, S. Klee, G. Mellau, H. Mäder, D. Walbrodt, M. Winnewisser, J. Mol. Spectrosc. 228 375 (2004)

– D. T. Petkie, T. M. Goyette, P. Helminger, H. M. Pickett, and F. C. De Lucia, J. Mol. Spectrosc. 208, 121 (2001)

– Coudert and Perrin, J. Mol. Spec. 172, 352 (1995)

Details of Torsional Models


-2000

-1500

-1000

-500

0

500

1000

Sig

na

l

104.480x103

104.475104.470Frequency/GHz

“Quad” transitions• Torsional Splitting ~ Asymmetry Splitting

– Torsional State Interactions (Dab terms) between Ka even odd

• Near equal intensities

6171: 14d,8 – 14d

9

Simulated

FASSST data


Range of Data SetJmax = Kc,max ~ 41Ka, max ~ 23rms ~ 400 kHz# transitions ~ 1000

Center of Fermi Interaction


Comments on the Analysis• Each state has it own torsional splitting parameter

– The “Fo” term is fixed to zero

• Torsional splitting suggests a 70/30 % mixing of the wavefunctions

– Assuming an isolated interaction

• Fermi term agrees with with Perrin, et al. and Wang, et al• Currently no need for a Coriolis interaction term• Distortional constants are well-behaved

– JK and K tend to become correlated in IAS models for HNO3 and higher in magnitude than expected (order of magnitude)

• Message data and assignments to finish the analysis– Quad transitions

• Add the infrared data from Perrin, et al. and Wang, et al. for 8+9

– Jmax = 74, Ka,max = 48

– check how well the ir data is predicted from the mw measurements

– Fit for Fo


Conclusions

• The pure rotational spectrum of 6171, 8191, and 21 excited vibrational states are well measured and characterized mm/submm wave region

• The stage is set for continued assignments and analysis of the set of ~6 states around 1300 cm-1

Documents

20 June 200661 st International Symposium on Molecular SpectroscopyPetkie – TG03-p1 The Millimeter and Submillimeter-wave Spectrum of the 8 1 9 1, 6 1