High Resolution Microwave Spectra of High Resolution Microwave Spectra of HeHeNN – and (H – and (H22))NN – Linear Molecule Clusters – Linear Molecule Clusters
Wolfgang Jäger
Department of Chemistry, University of Alberta, Edmonton, AB Canada
Collaborations:Yunjie Xu, UofABob McKellar, NRCPN Roy, Nick Blinov, UofA
(H(H22))NN – Molecule Clusters on this Meeting – Molecule Clusters on this Meeting
• MH15: H2 – C5H5NChakree Tanjaroon
• TE02: (H2)N – N2O, N up to 6Jen Landry
• TE03: (H2)N – OCS, N up to 7Julie Michaud
Wolfgang Jäger
Department of Chemistry, University of Alberta, Edmonton, AB Canada
Collaborations:Yunjie Xu, UofABob McKellar, NRCPN Roy, Nick Blinov, UofA
High Resolution Microwave Spectra of High Resolution Microwave Spectra of HeHeNN – Linear Molecule Clusters – Linear Molecule Clusters
Impetus for HeImpetus for HeNN-Molecule Studies-Molecule Studies• He – OCS, He – HF, etc. studies by Higgins and Klemperer.
• SF6, OCS Helium nanodroplet studies by the Scoles/Lehmann and Toennies/Vilesov groups.
• 50th OSU Symposium, Outstanding Challenges for Molecular Spectroscopy(compiled and distilled by Kevin Lehmann)
V. Towards a true Microscopic Theory of Condensed Matter…e) Improvements in experiments and theory of the size
dependence of molecular properties to better understand the transition from an isolated molecule – small cluster – condensed phase.
A Case in Point: SuperfluidityA Case in Point: Superfluidity
• 4He becomes superfluid below the λ-point (2.17 K).• Frictionless flow, irrotationality, quantized vorticity,
fountain effect …
Andronikashvili experiment
‘Drag’ from normal fluid component causes increase of moment-of-inertia of disk stack.
Confirmation of two–fluid model.
The Microscopic Andronikashvili ExperimentThe Microscopic Andronikashvili Experiment
Grebenev, Toennies, Vilesov, Science 279, 2083 (1998).
Pure 4He droplet
Pure 3He droplet
4He droplet with 20 3He
4He droplet with 40 3He
4He droplet with 60 3He
4He droplet with 1000 3He
Alberta:
Rotational (microwave) spectra of HeN-molecule clusters.Instrument: FTMW Spectrometer, 2.5 - 11 GHz.
Ottawa:
Ro-vibrational (infrared) spectra of HeN-molecule clusters.Instrument: Rapid Scan mid-IR Diode Laser spectrometer.
Instrument and TechniqueInstrument and Technique
Multidimensional Assignment ProcedureMultidimensional Assignment Procedure
• infrared predictions
• sample conditions (pressure, temperature)
• double resonance experiments
• consistency of isotopic data
• spectral fits
HeN-OCS
HeHeNN – Molecule Clusters – Molecule Clusters
Effect of Nozzle Cooling on Cluster FormationEffect of Nozzle Cooling on Cluster FormationHe6-OCS, J=3-2 at 11176.83 MHz, 0.01% OCS in He at 20.4 atm100 averaging cycles
nozzle at room temperatureS/N ~ 2
nozzle at dry ice temperature (-78.5 C)S/N ~ 40
Double Resonance SpectrometerDouble Resonance Spectrometer
Double Resonance SpectrometerDouble Resonance Spectrometer
Double Resonance Experiments on HeDouble Resonance Experiments on He66-OCS-OCS
signal: J-3-2, 11176.83 MHzpump: J=2-1, 7588.75 MHz20 averaging cycles
pump power(continuous)
off
-3 dBm
3 dBm
Double resonance experimentsalso with the ‘decoherence technique’.Brendel, Mäder, OSU Symposium2004, paper TA05.
Vibrational Frequency Shifts of HeVibrational Frequency Shifts of HeNN-OCS Clusters-OCS Clusters
experimental values,Tang et al., Science 297, 2030 (2002).
values from Whaley and co-workers, JCP 115, 10225 (2001).
Paesani, Whaley, JCP 121, 4180 (2004).
Vibrational Frequency Shifts of HeVibrational Frequency Shifts of HeNN-OCS Clusters-OCS Clusters
experimental values,Tang et al., Science 297, 2030 (2002).
values from Whaley and co-workers, JCP 115, 10225 (2001).
Moment-of-Inertia Shifts of IsotopomersMoment-of-Inertia Shifts of Isotopomers
I / amu2
32.2
48.8
35.7
37.4
32.1
Proposed Structure of HeProposed Structure of He88-OCS-OCS
Helium density in HeHelium density in He88-OCS-OCS
P. N. Roy, N. Blinov, private communication.
Spectroscopic Constants of HeSpectroscopic Constants of HeNN-OCS Clusters-OCS ClustersMolecule B / MHz D / MHz
Free OCS 6081.59 1.31x10-5
He-OCS 13208.57
5504.18 4582.80
3661.42
0.950
He2-OCS 5803.39
4546.34 3782.81
3019.28
---
He3-OCS 3104.57 5.11
He4-OCS 2591.95 0.881
He5-OCS 2225.15 0.234
He6-OCS 1910.49 2.60
He7-OCS 1682.98 1.29
He8-OCS 1447.73 2.00
OCS in 4He droplet
(N~3,000)
2194.5(90) 11.4(3)
Rotational Constant vs.Number of He AtomsRotational Constant vs.Number of He Atoms
Quantum Monte Carlo Calculations.Quantum Monte Carlo Calculations.
N. Blinov, X. Song, P. N. Roy, JCP 120, 5916 (2004).S. Moroni et al., Phys. Rev. Lett. 90, 143401 (2003).
Helium Density Profiles in HeHelium Density Profiles in HeNN-OCS-OCS
N. Blinov, X. Song, P. N. Roy, JCP 120, 5916 (2004).
N=5
N=7
N=9
N=6
N=8
N=10
HeN-N2O
HeHeNN – Molecule Clusters – Molecule Clusters
HeHe66-N-N22O in its Principal Inertial Axes SystemO in its Principal Inertial Axes System
J=1-0 Rotational TransitionJ=1-0 Rotational Transition
Inte
nsity
Inte
nsity
Frequency / MHz
He7-14N15NO
He5-14N15NOIn
tens
ity
He12-14N15NO
6792.0 6793.5
5471.5 5473.0
6194.5 6195.5
Rotational Constant vs.Number of He AtomsRotational Constant vs.Number of He Atoms
S. Moroni, N. Blinov, P. N. Roy, J. Chem. Phys 121, 3577 (2004).
Helium droplet valueNauta, Miller, JCP 115, 10254 (2001).
Xu, Jäger, Tang, McKellar, Phys. Rev. Lett. 91, 163401 (2003).
Xu, Jäger, Blinov, Roy, J. Chem. Phys. 124, 081101 (2006).
Helium Density Distributions in HeHelium Density Distributions in HeNN-N-N22OO
N=5
N=9
N=14
N=6
N=10
N=15
Back to HeN-OCS
HeHeNN – Molecule Clusters – Molecule Clusters
Infrared Spectra of HeInfrared Spectra of HeNN-OCS Clusters-OCS Clusters
2062.0 2062.1 2062.2 2062.3
R(0)Transitions
14
1516
1718
20
30
4070 6050
Wavenumber / cm-1
Bob McKellar, paper FD01
0
1e+8
2e+8
3e+8
4e+8
5e+8
6e+8
0
10
20
30
40
50
3000
4000
5000
6000
Am
plitu
de
N, n
umbe
r of h
eliu
m a
tom
s
Frequency / MHz
Nanodroplet value
νJ=1-0 ≈ 2B
J=1-0 MW Transitions of HeJ=1-0 MW Transitions of HeNN-OCS Clusters-OCS Clusters
νJ=1-0 ≈ 2B
400 kHz
0
1e+8
2e+8
3e+8
4e+8
5e+8
6e+8
0
10
20
30
40
50
3000
4000
5000
6000
Am
plitu
de
N, n
umbe
r of h
eliu
m a
tom
s
Frequency / MHz
J=1-0 MW Transitions of HeJ=1-0 MW Transitions of HeNN-OCS Clusters-OCS Clusters
Rudi Lehnig, RD05
7000
0
1e+8
2e+8
3e+8
4e+8
5e+8
6e+8
0
10
20
30
40
50
3000
4000
5000
6000
Am
plitu
de
N, n
umbe
r of h
eliu
m a
tom
s
Frequency / MHz
J=1-0 MW Transitions of HeJ=1-0 MW Transitions of HeNN-OCS Clusters-OCS Clusters
Rudi Lehnig, RD05
7000
Rotational Constant Rotational Constant BB as Function of Cluster Size as Function of Cluster Size
Number of helium atoms, N0 10 20 30 40 50 60 70
Ro
tatio
nal c
ons
tant
, B
" /
MH
z
1500
2000
2500
3000
*nanodroplet B-valueToennies, Vilesov, and co-workersJCP 112, 4485 (2000)
Experiment
S. Paolini et al., JCP 123, 114306 (2005).
Whaley and coworkers, PRL 90, 073401 (2003);JCP 121, 4180 (2004);JCP 123, 114301 (2005).
S. Moroni et al., PRL 90, 143401 (2003).
Rotational Constant Rotational Constant BB as Function of Cluster Size as Function of Cluster Size
Number of helium atoms, N0 10 20 30 40 50 60 70
Ro
tatio
nal c
ons
tant
, B
" /
MH
z
1500
2000
2500
3000
*nanodroplet B-valueToennies, Vilesov, and co-workersJCP 112, 4485 (2000)
Experiment
S. Paolini et al., JCP 123, 114306 (2005).
Whaley and coworkers, PRL 90, 073401 (2003);JCP 121, 4180 (2004);JCP 123, 114301 (2005).
S. Moroni et al., PRL 90, 143401 (2003).
AufbauAufbau of a Helium Solvation Shell Structure of a Helium Solvation Shell Structure
AcknowledgementsAcknowledgements
• Dr. Dominik Bremm• Dr. Rudi Lehnig (RD05)• Dr. Chakree Tanjaroon (MH15)• Jen Landry (TE02)• Julie Michaud (TE03)• Wendy Topic• Qing Wen (TE05)
• NSERC, CFI, ASRIP, University of Alberta, CRC
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