title: Accurate line shapes from sub-1 cm(-1) resolution sum frequency generation vibrational spectroscopy of α-pinene at room temperature.
abstract: Despite the importance of terpenes in biology, the environment, and catalysis, their vibrational spectra remain unassigned. Here, we present subwavenumber high-resolution broad-band sum frequency generation (HR-BB-SFG) spectra of the common terpene (+)-α-pinene that reveal 10 peaks in the C-H stretching region at room temperature. The high spectral resolution resulted in spectra with more and better resolved spectral features than those of the Fourier transform infrared, femtosecond stimulated Raman spectra in the bulk condensed phase and those of the conventional BB-SFG and scanning SFG spectroscopy of the same molecule on a surface. Experiment and simulation show the spectral line shapes with HR-BB-SFG to be accurate. Homogeneous vibrational decoherence lifetimes of up to 1.7 ps are assigned to specific oscillators and compare favorably to lifetimes computed from density functional tight binding molecular dynamics calculations. Phase-resolved spectra provided their orientational information. We propose the new spectroscopy as an attractive alternative to time domain vibrational spectroscopy or heterodyne detection schemes for studying vibrational energy relaxation and vibrational coherences in molecules at molecular surfaces or interfaces.
authors: Department of Chemistry, University of Puget Sound , Tacoma, Washington 98416, United States.
authors: Amanda L
authors: AL
authors: Mifflin
authors: Luis
authors: L
authors: Velarde
authors: Junming
authors: J
authors: Ho
authors: Brian T
authors: BT
authors: Psciuk
authors: Christian F A
authors: CF
authors: Negre
authors: Carlena J
authors: CJ
authors: Ebben
authors: Mary Alice
authors: MA
authors: Upshur
authors: Zhou
authors: Z
authors: Lu
authors: Benjamin L
authors: BL
authors: Strick
authors: Regan J
authors: RJ
authors: Thomson
authors: Victor S
authors: VS
authors: Batista
authors: Hong-Fei
authors: HF
authors: Wang
authors: Franz M
authors: FM
authors: Geiger
mesh_terms: D000081008:Bicyclic Monoterpenes; D008956:Models, Chemical; D056004:Molecular Dynamics Simulation; D039821:Monoterpenes / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods*; D013696:Temperature; D014732:Vibration
chemical_list: D000081008:Bicyclic Monoterpenes; D039821:Monoterpenes; C005451:alpha-pinene