THz Spectroscopy of 1d-ethane: Assignment of v 18 ADAM M. DALY, BRIAN J. DROUIN, LINDA BROWN Jet...
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Transcript of THz Spectroscopy of 1d-ethane: Assignment of v 18 ADAM M. DALY, BRIAN J. DROUIN, LINDA BROWN Jet...
THz Spectroscopy of 1d-ethane: Assignment of v18
ADAM M. DALY, BRIAN J. DROUIN, LINDA BROWNJet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109
PETER GRONERDepartment of chemistry , University of Missouri, Kansas City, MO.
18-Jun14 ISMS FE07
ISMS FE07
Motivation
18-Jun14
A window in the ethane spectrum? Avoiding q-branch ethane
• Astronomy
http://universe-review.ca/F07-planets06.htm
ISMS FE07
Motivation
18-Jun14
Assign v11= 715 cm-1 and v17 = 805 cm-1
in C2H5D and fit transitions to within the resolution of the measurement
Data taken with the Bruker 125 HR with 20.8 m path length.
Resolution 0.0028 cm-1
Temperature = 130 K
• Spectroscopy v11= 715 cm-1 v17 = 805 cm-1
4v18= 726 cm-1?
ISMS FE0718-Jun14
Motivation
v11= 715 cm-1 (A’) and v17 =805 cm-1(A”)
Dark state, 3 v18 at 726 cm-1 (A”)
ISMS FE07
Motivation
18-Jun14
• Spectroscopy
Assign v11= 715 and v17 = 805 in C2H5Dand fit transitions to within the resolution of the measurement
Data taken with the Bruker 125 HR with 20.8 m path length.
Resolution 0.0028 cm-1
Temperature = 130 K
v11= 715 v17 = 805
ISMS FE07
Motivation
18-Jun14
v17 = 715 in C2H5D
High Kc R-branch
v11= 715Q-branch Ka upper andLower zero
• Spectroscopy J1,J-1 ← J0,JJ0,J ← J1,J-1
ISMS FE07
Motivation
18-Jun14
• SpectroscopyA E A E A E A E A E A E A E
J1,J-1 <- J0,J1 2 3 4 5 6 7
30,2 <- 20,1
J=61,6 <- 52,3
v11= 715Q-branch Ka lower zero
ISMS FE07
Motivation
18-Jun14
• Spectroscopy v11= 715 v17 = 805
v17 = 805
ISMS FE07
Motivation
18-Jun14
• Spectroscopy4←3 5←4 6←5 7←6 8←7 9←8Ka”←Ka’v17 = 805
Q-branch Ka -> Ka+1
ISMS FE07
Motivation
18-Jun14
Clearly split by internal rotation
• Spectroscopy 152,13←141,13 161,15←150,15
v17 = 805
Q-branch Ka = 7 ← Ka= 6
111 8 J21 20 19 18 17 16 15 14 13 12 11 10 9 8 7
ISMS FE07
Background
18-Jun14
D
H
HH
H
H
Microwave spectra of deuterated ethanes: Internal rotation potential function and rz structure
E. Hirota, Y. Endo, S. Saito, J.L. Duncan, J. Mol. Spectrosc. 89 (1981) 285–295.
• Pure a-dipole 12 pairs A/E 2 R-branch (J=3 and 4) • b-dipole 15 pairs A/E that 2 R-branch (J=2 and 3) and 13 Q-branch (Ka 2<- 1)
TB03 OSU Conference 2013
BRIAN J. DROUIN, SHANSHAN YU, JOHN C. PEARSON, LINDA R. BROWN, KEEYOON SUNG, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109; PETER GRONER, Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110-2499. • The data set contains two Q-branch measurements (K = 5-6 and K = 9,10 , the first
with J up to 30) and a smattering of R-branch measurements up to J = 28 and K’s in the teens.
• There are 475 unique assignments, but many of these are for blended features.
ISMS FE07
Methods
18-Jun14
Ground state results
ISMS FE0718-Jun14
Experimental Setups
520-605, 680-800, 960-1240 GHz, 6 meter path, 1.2 K Silicon Bolometer, Static cell with amorphous quartz windows
MultiplierInlet Port Vacuum Port
Glass Cell 3m
RooftopReflector
Bolometer
Polarized Grid
Stanford Research Lock-in Amplifier
Preamp
16.78888 Ghz
Synthesizer
GPIB
ISMS FE0718-Jun14
Initial scans
ISMS FE0718-Jun14
Initial scans
ISMS FE0718-Jun14
Initial scans
ISMS FE0718-Jun14
Initial scans
ISMS FE0718-Jun14
Initial Scans
ISMS FE0718-Jun14
Initial Scans
ISMS FE0718-Jun14
ERHAM SPFITPure Rotation
A /MHz 69633.185(10) 69633.176(17)B /MHz 18774.4219(20) 18774.4207(21)C /MHz 18164.4825(20) 18164.4812(19)DJ /kHz 26.6122(24) 26.6099(10)DJK /kHz 68.538(33) 68.469(46)DK /kHz 241.69(12) 241.35(28)d1 /kHz -0.92184(67) -0.92106(81)d2 /kHz 0.12141(55) 0.12285(46)HJ /Hz -0.0055(28) -HJK /Hz 0.175(30) 0.158(27)HKJ /Hz 1.53(25) 0.31(28)HK /Hz - -8.76(134)
Tunneling terms ERHAM SPFIT 2*e10 /MHz 2253.10(22) 2252.62(24)2*e20 /MHz 0.471(16) 1.509(58)
r 0.4343990(81) [ 0.434401021]b / deg
0.873(75)
q / kHz -402.3(76) -640.2(85)
] q / kHz
45.3(64) -21.99(94)
/kHz
-30.9(31) -116.98(51)
/ kHz
0.569(46) -33.4(16)
] / kHz
-1.48(37) -
/kHz 2.83(19) -
/kHz 0.00283(19) 0.00346(36) /kHz - 0.00231(37) /kHz - -0.00151(21) /kHz .305(34) 0.286(81) /kHz - -58(20) /kHz -0.00134(49) -0.00154(27)
/kHz -0.0333(57) 0.080(31)
/kHz - 7.5(35) /kHz - -0.00154(27) /kHz - -0.000309(26)
/mHz - -Dab / kHz 1693.(202) -
Final fit of v18
TORSIONAL ENERGY DIFFERENCES (MHz)
v18 (A-E) = -3381.8516 +/- 0.2667
v18 fitState 00: 163 lines MICROWAVE RMS = 0.268358 RMS ERROR = 1.130830 State 10: 164 lines MICROWAVE RMS = 0.349844 RMS ERROR = 1.344719
ISMS FE0718-Jun14
ERHAM SPFITPure Rotation
A /MHz 69633.185(10) 69633.176(17)B /MHz 18774.4219(20) 18774.4207(21)C /MHz 18164.4825(20) 18164.4812(19)DJ /kHz 26.6122(24) 26.6099(10)DJK /kHz 68.538(33) 68.469(46)DK /kHz 241.69(12) 241.35(28)d1 /kHz -0.92184(67) -0.92106(81)d2 /kHz 0.12141(55) 0.12285(46)HJ /Hz -0.0055(28) -HJK /Hz 0.175(30) 0.158(27)HKJ /Hz 1.53(25) 0.31(28)HK /Hz - -8.76(134)
Tunneling terms ERHAM SPFIT 2*e10 /MHz 2253.10(22) 2252.62(24)2*e20 /MHz 0.471(16) 1.509(58)
r 0.4343990(81) [ 0.434401021]b / deg
0.873(75)
q / kHz -402.3(76) -640.2(85)
] q / kHz
45.3(64) -21.99(94)
/kHz
-30.9(31) -116.98(51)
/ kHz
0.569(46) -33.4(16)
] / kHz
-1.48(37) -
/kHz 2.83(19) -
/kHz 0.00283(19) 0.00346(36) /kHz - 0.00231(37) /kHz - -0.00151(21) /kHz .305(34) 0.286(81) /kHz - -58(20) /kHz -0.00134(49) -0.00154(27)
/kHz -0.0333(57) 0.080(31)
/kHz - 7.5(35) /kHz - -0.00154(27) /kHz - -0.000309(26)
/mHz - -Dab / kHz 1693.(202) -
Final fit of v18
Ground stateState 00: 298 lines MICROWAVE RMS = 0.214684 RMS ERROR = 0.900575 State 10: 469 lines MICROWAVE RMS = 0.334478 RMS ERROR = 0.952100
TORSIONAL ENERGY DIFFERENCES (MHz) ground state (A-E) = 74.1616 +/- 0.0366 MHz v18 (A-E) -3381.8516 +/- 0.2667 MHz
v18 fitState 00: 163 lines MICROWAVE RMS = 0.268358 RMS ERROR = 1.130830 State 10: 164 lines MICROWAVE RMS = 0.349844 RMS ERROR = 1.344719
ISMS FE0718-Jun14
Table 3. Potential parameters in cm-1, relative to the potential minimum, F was fixed at 28259 MHz.
Parameter Hirota* Fernandez* All V3 1009.5 1005.8(37) 1003.50(7) V6 - 7.(3) 7.26(33) *values derived from spectral line positions reported in these studies
Table 4. Torsional levels in cm-1 relative to the zero-point energy based on potential fit parameters in Table 3.
Level Hirota* Fernandez* All 4(A) 269.46 271.51 271.11 4(E) 269.57 271.62 271.22 24(E) 510.91 513.32 512.54 24(A) 512.91 515.38 514.62 34(A) 714.12 715.16 713.98 34(E) 732.98 734.72 733.68 44(E) 849.25 847.96 846.44 44(A) 904.87 904.51 903.16 *values derived from spectral line positions reported in these studies
Using the ground state, v18 and Raman data
E. Hirota, Y. Endo, S. Saito, J.L. Duncan, Microwave spectra of deuterated ethanes: Internal rotation potential function and rz structure, J. Mol. Spectrosc. 89 (1981) 285–295. doi:10.1016/0022-2852(81)90024-2.J,M. Fernandez and S. Montero, J. Chem. Phys. 94, 7788 (1991)
ISMS FE07
Potential Fit
18-Jun14
-200 -150 -100 -50 0 50 100 150 2000
200
400
600
800
1000
1200
656 cm-1
654 cm-1
413.3 cm-1
413.2 cm-1
142.06 cm-1
142.08 cm-1
875 cm-1
856 cm-1
G.S.
vt=1.
vt=2.
vt=3.
ISMS FE07
Conclusions: Future directions from TB03 (2013)
18-Jun14
• Retrieved positions and intensities up to 860 cm-1 (done)– Challenging spectrum 9000 features 700-850 cm-1
• Complete assignments IR spectrum in 700 - 860 cm-1 range • to v11, v17 and perhaps 3vt (overtone) (in progress)• Develop Effective Hamiltonian and model observed positions and
intensities (in progress)• Create a linelist to enable the first detection of this species in
outer planets. (in progress)
ISMS FE0718-Jun14
Acknowledgements
• Brian Drouin• Linda Brown• John Pearson• Peter Groner