BEGIN:VCALENDAR VERSION:2.0 PRODID:-//ZContent.net//ZapCalLib 1.0//EN CALSCALE:GREGORIAN METHOD:PUBLISH BEGIN:VEVENT SUMMARY:Ultrafast Nonlinear IR Spectroscopy for Exotic Molecular Materials LOCATION:Chemistry A101 TZID:America/Denver DTSTART:20189201T000000 UID:2026-04-18-17-52-08@natsci.colostate.edu DTSTAMP:20260418T175208 Description:In this seminar\, I will discuss two developments in ultrafast nonlinear IR spectroscopy for exotic molecular materials: (1) 2D IR spectr oscopy for molecular vibrational polaritons and (2) transient electric fie ld induced VSFG spectroscopy for probing interfacial charge transfer. Both show the advantages of ultrafast nonlinear IR spectroscopic technique: to decipher hidden physics of exotic molecular materials.\n\n2D IR of Molecu lar Polaritons.1 Molecular vibrational polaritons\, half-light\, half-matt er hybrid quasiparticles\, are studied using ultrafast\, coherent 2D IR sp ectroscopy. Molecular vibrational-polaritons are anticipated to produce ne w opportunities in the photonic and molecular phenomena. Many of these dev elopments hinge on fundamental understanding of physical properties of mol ecular vibrational polaritons. Using 2D IR spectroscopy to study vibration al-polaritons\, we obtained results that challenge and advance both polari ton and spectroscopy fields. These results invoke new developments in theo ry for the spectroscopy\, discover observation of new nonlinear optical ef fects and unexpected responses from hidden dark states. We expect these re sults to have significant implications in novel infrared photonic devices\ , lasing\, molecular quantum simulation\, as well as new chemistry by tail oring potential energy landscapes.\n\nTransient E-field induced VSFG for D irect Interfacial Charge Transfer.2 We describe direct electron-transfer a t buried interfaces between an organic polymer semiconductor film and a go ld substrate\, by observing the transient electric-field-induced vibration al sum frequency generation (VSFG).  We observe dynamic responses (<\;1 50 fs) where electrons are directly transferred from the Fermi level of go ld to the LUMO of organic semiconductor. Transient spectra further reveal that\, although the interfaces are prepared without deliberate alignment c ontrol\, a sub-ensemble of surface molecules can adopt conformations for d irect electron transfer\, supported by DFT calculations. This result will have implications for implementing novel direct electron transfer in energ y materials.\n\nReferences.\n\n Xiang\, B. et al. Two-dimensional infrare d spectroscopy of vibrational polaritons. Proc. Natl. Acad. Sci. 115\, 484 5–4850 (2018).\n Xiang\, B.\, Li\, Y.\, Pham\, C. H.\, Paesani\, F. &am p\; Xiong\, W. Ultrafast Direct Electron Transfer at Organic Semiconductor and Metal Interfaces. Sci. Adv. 3\, e1701508 (2017).\n 4:00 pm END:VEVENT END:VCALENDAR