20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p1 The Millimeter and Submillimeter-wave Spectrum of the , , and 2 1 Vibrational States of Nitric Acid Douglas T. Petkie Department of Physics, Wright State University Paul Helminger Department of Physics, University of South Alabama Ivan R. Medvedev, Atsuko Maeda, Frank C. De Luica Department of Physics, Ohio State University International Symposium on Molecular Spectroscopy 61 th Meeting June 19-23, 2006 The Ohio State University Columbus, Ohio

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p2 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

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p3 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.

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p4 Nitric Acid Vibrational Levels assignments and initial analyses Published analyses  a = 1.98 D  b = 0.88 D a-type  K a = 0,  2  K c =  1,  3 b-type  K a =  1,  3  K c =  1,  3 N OO O H Current Focus

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p5 Interference fringes Spectrum InSb detector 1 InSb detector 2 Ring cavity: L~15 m Mylar beam splitter 1 Mylar beam splitter 2 High voltage power supply Slow wave structure sweeper Aluminum cell: length 6 m; diameter 15 cm Trigger channel /Triangular waveform channel Signal channel BWO Magnet Lens Filament voltage power supply Length ~60 cm Stepper motor Reference channel Lens Stainless steel rails Path of microwave radiation Preamplifier Frequency roll-off preamplifier Reference gas cell Glass rings used to suppress reflections Data acquisition system Computer FAst Scan Submillimeter Spectroscopic Technique (FASSST) spectrometer WI04: FAST SCAN SUBMILLIMETER SPECTROSCOPIC TECHNIQUE (FASSST).

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p6 FASSST Data GHz, Heated ~180 o C, Signal averaged data ~ time constant ~ 20 msec plus “legacy data” ( GHz synthesizer and older FASSST data)

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p7 R and Q Branches FASSST Spectra Simulation of ground state

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p8 Assignment Methodology 106 GHz region Frequency /GHz Signal/au

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p9 Relevant Studies of  2 = 1 2 High-resolution infrared studies (b-type transitions): –Laser Diode: C. H. Bair and P. Brockman, Appl. Opt. 18, (1979) A. G. Maki and J. S. Wells, J. Mol. Spectrosc. 82, (1980) A. Maki, J. Mol. Spectrosc. 127, (1988) –15 MHz, 1680 – 1738 cm -1, J = 66, K a = 35, K c = 60 –No perturbations: »few low K a do not fit: , cm -1 –FTIR: T.L. Tan, et al., J. Mol. Spectrosc. 155, (1992) –15 MHz, J = 72, K a = 45, K c = 72 – , cm -1, K a ≤ 7 (J~64) »obs-calc max = 245 MHz ( cm -1 ) »Severely overlapped, as with Maki »Excluded from analysis and not understood

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p10  2 = 1 Assignments and Spectra

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p11 R-Branch Summary Infrared transitions obs-calc up to 245 MHz R = Fitted Transition RP = well predicted clear region, missing transition RP? = well predicted but congested * = no spectra available

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p12 Q-Branch Summary Infrared transitions obs-calc up to 245 MHz Q = Fitted Transition QP = well predicted clear region, missing transition QP? = well predicted but congested * = no spectra available

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p13  2 = 1 Spectroscopic Parameters and Summary Starting point was Tan, et al. constant set Watson A-reduced Hamiltonian in the I r representation 207 fitted transitions between GHz Maximum Quantum Numbers J = 40, K a = 19, K c = kHz rms deviation Constants in fairly good agreement with ir work Possibility of perturbation Spectral congestion

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p14 Infrared Laboratory Spectrum

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p15 Nitric Acid Vibrational Levels assignments and initial analyses Published analyses  a = 1.98 D  b = 0.88 D a-type  K a = 0,  2  K c =  1,  3 b-type  K a =  1,  3  K c =  1,  3 N OO O H Current Focus

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p16 Previous Studies for  and A. G. Maki, J. Mol. Spectrosc. 136, 105–108 (1989). –Infrared Spectrum of the 1205 cm -1 Band of HNO 3 T. M. Goyette and F. C. De Lucia, J. Mol. Spectrosc. 139, 241–243 (1990). –The millimeter and Submillimeter Wave Spectrum of the State of HNO 3 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 and the Dark State of HNO 3 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 Band of HNO 3, Line Positions and Intensities, and Resonances Involving the v 6 = v 7 = 1 Dark State

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p and Assignments and Spectra Predicted Spectra X50 vertical scale FASSST Spectra

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p18  6 =  7 =1 Assignments and Spectra R-Branch “Triplets”

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p19 Torsional Effects on the Spectrum J+1 0,J+1 J+1 1,J+1 J+1 0,J+1 J 0,J J 1,J J 0,J a-typeb-type R-Branch o b-type

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p20 Torsional Splitting Summary StateObserved Splitting in MHz 9 77 Not resolved 9 6 Triplet b b a 316 GHz region Frequency/MHz Signal/au

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p21 IAS Hamiltonian: and States IAS (Internal Axis System) Hamiltonian –SPFIT, SPCAT (Pickett /JPL) I R representation in the A-reduction (z = a, x = b, y = c) Interaction terms –Fermi and c-type Coriolis terms

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p22 General –H. M. Pickett, J. Chem. Phys. 107, 6732 (2001) –Hougen, J. Mol. Spectrosc. 114, 395 (1985) HNO 3 –A. Perrin, J. Orphal, J.-M. Flaud, S. Klee, G. Mellau, H. Mäder, D. Walbrodt, M. Winnewisser, J. Mol. Spectrosc (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

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p23 “Quad” transitions Torsional Splitting ~ Asymmetry Splitting –Torsional State Interactions (D ab terms) between K a even  odd Near equal intensities : 14 d,8 – 14 d 9 Simulated FASSST data

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p24 Range of Data Set J max = K c,max ~ 41 K a, max ~ 23 rms ~ 400 kHz # transitions ~ 1000 Center of Fermi Interaction

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p25 Comments on the Analysis Each state has it own torsional splitting parameter –The “F o ” 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 HNO 3 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 –J max = 74, K a,max = 48 –check how well the ir data is predicted from the mw measurements –Fit for F o

20 June st International Symposium on Molecular SpectroscopyPetkie – TG03-p26 Conclusions The pure rotational spectrum of , , and 2 1 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