The ultraviolet spectroscopy of phenylcyclopentene and phenylcyclopentadiene. Josh J. Newby, Ching-Ping Liu, Christian Müller and Timothy S. Zwier FD02 Department of Chemistry, Purdue University West Lafayette, IN 47907
2 stage ion acceleration pulsed valve laser port diffusion pump cryocooler Einzel lens mass gate pulser ground plate MCP Origins of Phenylcyclopentenes Electrodes Reaction channel Insulator II C6C6 C7C7 C8C8 C9C9 C 10 C 11 C 12 WI06 Butadiene Discharge
What is m/z 142? Benzene discharge Vinylacetylene discharge Personal Communication T. Schmidt 2006 Butadiene discharge II C6C6 C7C7 C8C8 C9C9 C 10 C 11 C 12 UVMPI
-methylstyrene and beyond ~72 cm -1 ? ?
Cools gas phase molecules to effective temperatures of a few degrees Kelvin Jet-cooled UV spectrum Boltzmann distribution of the vibrational population prior to expansion Collisional cooling to zero-point vibrational level B* C E C C B A D A C A A B C C A A E B B B B B D UV C UV-chromophore A Jet-Cooled Spectroscopy
Resonant 2 Photon Ionization (R2PI): MS to UV Spectrum R2PI S1S1 S0S0 Ion
Synthesis of phenylcyclopentadiene 1 7 Bernard-Henriet, C. and Chanon M. Tetrahedron letters 37(14) PCP4D PCP3D
Cyclopentadiene dimer Δ 170
Identification of Phenylcyclopentadiene (PCPD) Synthetic Discharge or
Identification of phenylcyclopentene (PCP) a) b) Commercial Discharge
UVHB S1S1 S0S0 Hole-burn Probe B* C E C C B A D A C A A B C C A A E B B B B B D Probe C A Hole-burn nsec UV Hole-burn UV probe Isomer and Conformation Selectivity UV Holeburning Spectroscopy UV Hole-burn laser fixed: Provides selectivity UV probe laser tuned Records the UV spectrum of a single conformation free from interference from others present in the expansion
R2PI A B UVHB of PCPD and PCP * R2PI * *
Phenylcyclopentadienes (PCPD)
Phenylcyclopentenes Twisted ~19 Heavy atom planar ~ 0 Twisted ~29 One Conformation Gaussian 03 B3LYP G (d,p) PCP3DPCP4DPCP One Conformation Gaussian 03 B3LYP G (d,p) One Conformation Gaussian 03 B3LYP G (d,p)
Progression of phenylcyclopentene 6a 6b 12
PCP Excited State Torsion Gaussian 03 CIS 6-31+G (d,p)
UV laser tuned A (S 0,v=0) A * (S 1 ) Detect total fluorescence UV laser Fixed Total fluorescence CCD Laser Induced Fluorescence (LIF) Single Vibronic Level Fluorescence (SVLF) Fluorescence Techniques PMT
SVLF of PCP 6a6b18
PCP Ground State Torsion Gaussian 03 B3LYP G (d,p)
PCP3D Ground State Torsion
Origin SVLF of PCP3D
Laser Induced Fluorescence Chamber To Roots pump PMT Carrier gas UV beam y x z Lens Mirror Pulsed valve Expansion
Origin Dispersed Fluorescence
Dispersed Fluorescence PCP
LIF of PCPD X/D ~10 R2PI
Dispersed Fluorescence of PCPD
Dispersed Fluorescence Cont.
LIF PCPD X/D~5 71
Conclusions 1 Conformation of each species –PCP, PCP3D, PCP4D Torsional Motions of PCP –Harmonic excited –Anharmoic, distorted ground All three seem to play a role in PAH formation
Dispersed Fluorescence of +71
Acknowledgements Professor Timothy S. Zwier U.S. Department of Energy National Aeronautics and Space Administration The Zwier Group Esteban BaqueroTG11 V. Alvin ShubertTG08, RA07, FD07 Tracy LeGreveTF13 Nathan Pillsbury William JamesTG12 Chirantha RodrigoRA09 Josh Sebree Dr. Jaime Stearns Dr. Talitha Selby Dr. Jasper Clarkson Dr. Ching-Ping Liu*FD01 Dr. Christian MüllerRA10
Pressure Study
The Zwier Group
Acknowledgements Professor Timothy S. Zwier The Zwier Group Esteban Baquero V. Alvin Shubert Tracy LeGreve Nathan Pillsbury William James Chirantha Rodrigo Josh Sebree Dr. Jaime Stearns* Dr. Talitha Selby Dr. Jasper Clarkson Dr. Ching-Ping Liu* Dr. Christian Müller U.S. Department of Energy National Aeronautics and Space Administration
Interesting Spectra m/z 142 m/z 144
Finding 142 and 144 m/z 142m/z 144
Discharge C4H6C4H6 Reaction Quenched by Expansion C6H6C6H6 C 12 H 10 C9H8C9H8 C4H6C4H6 C4H6C4H6
Phenylcyclopentadienes Top: Synthetic Right: Discharge
Phenylcyclopentadi-1,4-ene
Conformation by IR ss ring as ring as CH ss CH2 Gaussian 03 B3LYP G (d,p)
S1S1 S0S0 IR Probe B* C E C C B A D A C A A B C C A A E B B B B B D Probe C A IR nsec IRUV probe RIDIRS Resonant Ion Dip IR Spectroscopy IR tuned UV probe laser fixed Records the IR spectrum of a single conformation free from interference from others present in the expansion Ion
RIDIRS
Progression of phenylcyclopentene ~72 cm -1
Synthesis of Phenylcyclopentadiene Bernard-Henriet, C. and Chanon M. Tertahedron letters 37(14)