1. CHIRALITY DETERMINATION FROM PULSED-JET FOURIER TRANSFORM
MOLECULAR STRUCTURE
AND
CHIRALITY DETERMINATION
FROM PULSED-JET FOURIER TRANSFORM
MICROWAVE SPECTROSCOPY
SIMON LOBSIGER, CRISTOBAL PEREZ, LUCA EVANGELISTI, NATHAN A. SEIFERT,
BROOKS H. PATE, KEVIN K. LEHMANN Department of Chemistry, University of Virginia

2. Background Mirror reflection: sign of mambmc changes
E. Hirota, Proc. Jpn. Acad., Sec B, 2012, 88, 120.
Background
D. Patterson, M. Schnell and J. M. Doyle, Nature, 2013, 497, 475
D. Patterson and J. M. Doyle, Phys. Rev. Lett., 2013, 111,
Mirror reflection: sign of mambmc changes
Cycle of three dipole-allowed transitions (a-, b- and
c-type) between rotational states:
Three-wave mixing experiment
Two orthogonally polarized resonant fileds 
third mutually orthogonal field encoding the chiral signal
and shift 180 degrees between enantiomers

3. Three Wave Mixing 2 11 2 02 1 01 Coherence Transfer 𝜋 pulse Coherence
J.-U. Grabow, Angew. Chem. Int. Ed., 2013, 52, 11698
Three Wave Mixing
K. K. Lehmann, unpublished X Z Y
Coherence Transfer
𝜋 pulse
Ψ = 𝑐 1 (t) 𝑐 2 (𝑡) 𝑐 3 (𝑡)
2 11
Coherence
2 02
𝜋 2 pulse
Ψ = 𝑐 1 (t) 𝑐 2 (𝑡)
Chiral Signal
1 01
Θ 𝑅𝑎𝑏𝑖 = 𝜔 𝑅𝑎𝑏𝑖 ∙ 𝑡 𝑝𝑢𝑙𝑠𝑒 = − 𝜇∙𝐸 ℏ ∙ 𝑡 𝑝𝑢𝑙𝑠𝑒
𝑃 𝑋 ∼𝝁 𝒂 𝝁 𝒃 𝝁 𝒄 Φ 𝑋𝑧 Φ 𝑌𝑥 Φ 𝑍𝑦
Considerations: -Signal a DP of p/2 pulse
-Signal a [nChiral Signal][mChiral Signal]
-Q-Branch involved (low frequency)

4. Experimental setup X Z Y Z Y X

5. R S Solketal 𝝁 𝒂 -1.8 D 1.8 D 𝝁 𝒃 1.2 D 1.2 D 𝝁 𝒄 -0.2 D -0.2 D
m06-2x/ g(d,p)
A = 2756 MHz
B = 1248 MHz
C = 1088 MHz
𝝁 𝒂 D
1.8 D
𝝁 𝒃 D
1.2 D
𝝁 𝒄 D
-0.2 D
𝝁 𝒂 𝝁 𝒃 𝝁 𝒄 + -

6. Broadband spectrum 2-8 GHz
Measured
Noise Level: 0.4 mV
400,000 Averages
a-type (4604 MHz)
b-type (1839 MHz)
c-type (6443 MHz)
1.5K Simulation of Solketal Rotational Spectrum Fit
Substitution Structure from 13C and 18O Isotopic Analysis (Natural Abundance)
m06-2x/ g(d,p)
mp2/ g(d,p)
* Cristóbal Pérez, Simon Lobsiger, Nathan A. Seifert, Daniel P. Zaleski, Berhane Temelso, George C. Shields, Zbigniew Kisiel, and Brooks H. Pate, “Broadband Fourier Transform Rotational Spectroscopy for Structure Determination: The Water Heptamer (Frontiers Article)”, Chem. Phys. Lett. 571, 1-15 (2013).

7. Experimental Design & Implementation
2 11
2 02
𝜋 pulse
𝜋 2 pulse
b-type (1839 MHz)
a-type (4604 MHz)
1 01
c-type (6443 MHz)
R-Branch weakest dipole moment
MW power DP
Detection in the strongest
𝜋 pulse Second weakest (Q-Branch)

8. Rabi Excitation Characteristics
𝜇 𝑎 = 1.8 D
𝜇 𝑏 = 1.2 D
𝜇 𝑐 = 0.2 D
𝜋 2 pulse
Θ 𝑅𝑎𝑏𝑖 = 𝜔 𝑅𝑎𝑏𝑖 ∙ 𝑡 𝑝𝑢𝑙𝑠𝑒 = − 𝜇∙𝐸 ℏ ∙ 𝑡 𝑝𝑢𝑙𝑠𝑒

9. Rabi Excitation Characteristics
𝜇 𝑎 = 1.8 D
𝜇 𝑏 = 1.2 D
𝜇 𝑐 = 0.2 D
𝜋 pulse
Θ 𝑅𝑎𝑏𝑖 = 𝜔 𝑅𝑎𝑏𝑖 ∙ 𝑡 𝑝𝑢𝑙𝑠𝑒 = − 𝜇∙𝐸 ℏ ∙ 𝑡 𝑝𝑢𝑙𝑠𝑒

10. Spectrum of Chiral Signal
2 11
2 02
𝜋 pulse
𝜋 2 pulse
b-type (1839 MHz)
a-type (4604 MHz)
1 01
c-type (6443 MHz)
Directly Digitized 50Gs/s
Filtered Frequencies

11. Enantiomer Dependent Phase11

12. Carvone: New conformer EQ3
Absolute Phase Measurements
Solketal
Carvone: New conformer EQ3
Others
EQ EQ EQ3

13. Conclusions Easy to implement at higher frequency
Three wave mixing: Time separated pulses tested successfully
Best Implementation: Optimal sequence
𝜋 2 pulse to create coherence
𝜋 pulse coherence transfer
Sizeable Chiral Signals
Issues with the absolute phase determination.

14. Thanks for your attention!!
Acknowledgements
National Science Foundation (NSF) grants CHE
Kevin Lehmann
Thanks for your attention!!

15. Spectrum of Chiral Signal
Fit of both MW pulses.
Product generates a “marker” that
can be directly compared to the
filtered molecular signal.
Phase can be compared across the FID

16. Absolute Phase Measurements
fR = -2.14(67)
fS = 1.29(84)