Rotational Spectra of N 2 O-H 2 Complexes University of Alberta Jen Nicole Landry and Wolfgang Jäger June 23, 2005
2 Motivation Stepping stone for the study of larger N 2 O-(H 2 ) N clusters. Possible observation of superfluidity in N 2 O-(pH 2 ) N. Previous studies: N 2 O-He and N 2 O-H 2 in the infrared region 1,2. N 2 O-He in the microwave region 3. 1 Tang & McKellar, JCP 117, 2586 (2002); 2 Tang & McKellar, JCP 117, 8308 (2002); 3 Song, Xu, Roy & Jäger, JCP 121, (2004).
3 Nuclear Spin States N 2 O-pH 2 & -oD 2 are expected to exhibit similar behaviors as N 2 O- 4 He. J. Tang & A. R. W. McKellar, JCP, 117, 8308 (2002). pH2pH2 oD2oD2 oH2oH2 pD2pD2 I total = 0 I total = 0,2 I total = 1 j H = 0,2... j H = 0,2… j H = 1,3...
4 Microwave Fourier Transform Spectrometer Sample cell is a Fabry-Perot microwave cavity. Pulsed excitation-spontaneous emission technique. Microwave frequency range from 4 to 26 GHz. Sample Composition: 0.25% N 2 O, 5% H 2 in He at 7 atm.
5 Observed Rotational Transitions Two a-type and two b-type transitions for 14 N 14 NO-pD 2 and 14 N 15 NO-pD 2. One a-type and two b-type transitions for 15 N 14 NO-pD 2 and 15 N 15 NO-pD 2. One a-type transition for 14 N 14 NO-oH 2. Nuclear quadrupolar hyperfine structures due to 14 N ( I = 1) and pD 2 ( I total = 1) nuclei. J. Tang & A. R. W. McKellar, JCP, 117, 8308 (2002).
6 Energy Level Diagram Energy JKaKcJKaKc
7 J K a K c = Transition of 14 N 14 NO-pD 2 Frequency (MHz) 1,2,3 - 1,2,3 2,3,3 - 1,2,2 1,0,1 - 1,1,2 F 1 ’,F 2 ’,F’- F 1 ”,F 2 ”,F” ,1,2 - 1,1,2 2,3,4 - 1,2,3 1,1,2 - 1,0,1 2,2,2 - 1,1,1 2,2,3 - 1,1,2 1,1,1 - 1,0,1 1,2,3 - 1,2,3
8 J K a K c = Transition of 14 N 14 NO-pD 2 Frequency (MHz) F 1 ’,F 2 ’,F’- F 1 ”,F 2 ”,F” 1,2,3 - 1,2,3 2,2,3 - 1,1,2 0,1,2 - 1,2,3 2,3,3 - 1,2,2 2,3,4 - 1,2,
9 14 N 14 NO-pD 2 Constants *J. Tang & A. R. W. McKellar, JCP, 117, 8308 (2002). ConstantsValues (MHz)ConstantsValues (MHz) A (5) aa ( 14 N-outer) (2) B (6) bb ( 14 N-outer) 0.299(6) C (4) cc ( 14 N-outer) 0.360(6) JJ 0.153* aa ( 14 N-inner) (3) JK 2.64* bb ( 14 N-inner) 0.08(1) KK 0.024* cc ( 14 N-inner) 0.192(1) JJ * aa (D 2 ) (5) KK 1.200* bb (D 2 ) (9) (kHz) 1.7 cc (D 2 ) 0.235(9)
10 J K a K c = Transition of 14 N 15 NO-pD 2 Frequency (MHz) 1,0 - 1,1 1,2 - 1,1 2,2 - 1,2 2,3 - 1,2 0,1 - 1,2 F 1 ’,F’- F 1 ”,F” 1,1 - 1,0 2,1 - 1,
11 J K a K c = Transition of 14 N 15 NO-pD 2 Frequency (MHz) 0,1 - 1,1 2,3 - 1,2 1,2 - 1,2 F 1 ’,F’- F 1 ”,F”
12 14 N 15 NO-pD 2 Constants ConstantsValues (MHz)ConstantsValues (MHz) A (6) aa ( 14 N-outer) (2) B (8) bb ( 14 N-outer) 0.305(2) C (7) cc ( 14 N-outer) 0.371(4) JJ 0.153* aa (D 2 ) (1) JK 2.64* bb (D 2 ) (6) KK 0.024* cc (D 2 ) (9) JJ * KK 1.200* (kHz) 1.6 *J. Tang & A. R. W. McKellar, JCP, 117, 8308 (2002).
13 J K a K c = Transition of 14 N 14 NO-oH 2 Frequency (MHz)
14 Ab initio Calculations Program: MOLPRO Method: CCSD(T) Basis Set: aug-cc-pVTZ Midbond functions: 3s 3p 2d 1f 1g s,p = 0.9, 0.3, 0.1 d = 0.6, 0.2 f,g = 0.6, 0.2 Basis Set Superposition Error (BSSE) was eliminated by applying the Counterpoise correction.
15 Spatial Configurations H 2 -axis along R H 2 -axis ┴ R & In-plane H 2 -axis ┴ R & Out-of-Plane R θ
16 Potential Energy Surfaces H 2 -axis along R PE= cm -1 R= 4.25 Å θ= 165° PE= cm -1 R= 4.50 Å θ= 0° H 2 -axis ┴ R & In-plane PE= cm -1 R= 3.00 Å θ= 90° PE= cm -1 R= 4.25 Å θ= 180° H 2 -axis ┴ R & Out-of-plane PE= cm -1 R= 3.00 Å θ= 90° PE= cm -1 R= 4.25 Å θ= 180° R (Å) Energies in cm -1
17 Comparison of ab initio & Experimental Data J K a K c ’-J K a K c ” Observed Transitions (MHz) H 2 -axis along R (MHz) H 2 -axis ┴ R & In-plane (MHz) H 2 -axis ┴ R & Out-of-Plane (MHz)
18 Future Work Assign rotational spectra of 14 N 14 NO-oH 2. Observe rotational transitions of N 2 O-pH 2 and N 2 O-oD 2. Create potential energy hybrid surface to predict bound state energies for the N 2 O-H 2 complexes. Measure higher order clusters for all N 2 O-H 2 isotopomers.
19 Acknowledgments Qing Wen Jäger and Xu Groups And YOU!!!