We report a femtosecond time-resolved photoelectron spectroscopic study of the excited state dynamics of spiropyran (SP3mt) in the gas phase. Using 266 nm pump and 200 nm probe pulses with an overall instrument response function of 160 fs, the experiment directly resolves the complete early-time evolution following photoexcitation. Following rapid internal conversion (SP–S2 → SP–S1), the excited-state population bifurcates into two competing pathways with a branching ratio close to 70/30: one channel leads to merocyanine formation via a multi-configurational excited state, and the other channel involving intersystem crossing (ISC) to a long-lived triplet-state (T2) manifold. Calculations at the MS-CASPT2/6-31G* level support the spectral assignments and the identification of the key transient intermediates. Our results provide a comprehensive picture of isolated spiropyran photoisomerization dynamics and clarify the elementary branching dynamics that control the competition between productive ring opening and nonreactive relaxation.
Uracil, a fundamental RNA nucleobase, exhibits complex excited-state dynamics governed by nonadiabatic processes that prevent photodamage. Upon photoexcitation, population initially reaches the bright ππ* (S2) state and subsequently relaxes to the dark nπ* (S1) state via conical intersections, before returning to the g...
Bonasree Roy, E. Titov, P. Saalfrank· ACS Omega· 0 citations
Excited-state intramolecular proton transfer (ESIPT) and subsequent photoisomerization in o-hydroxy Schiff bases are central to many photochromic and fluorescent applications, yet the interplay between proton transfer and torsional relaxation in the simplest member of this family remains poorly understood. Here, we pre...
Arshad Mehmood· Journal of Physical Chemistr...· 0 citations
The ultrafast Rydberg-state dynamics of N-methyl morpholine following photoexcitation at 160 nm is investigated using the femtosecond time-resolved photoelectron imaging method. The 3d → 3p → 3s sequential decay mechanism is proposed, as supported by the present time-, energy-, and angle-resolved photoelectron spectros...
Yu-Huan Tian, Yu-Kun Dan, Wen-Ping Wu et al.· Physical Chemistry, Chemical...· 0 citations
Dibenzoterrylene (DBT) is an organic single-photon emitter widely studied for applications in quantum optics and molecular photonics. Although DBT is not typically regarded as a highly flexible molecule, its energy landscape exhibits multiple low-energy conformations with distinct vibrational and electronic properties....
Royle Perez-Castillo, B. Weight, S. Tretiak et al.· Physical Chemistry, Chemical...· 0 citations
The photophysics and photochemistry of the BODIPY phenol derivative 1 were investigated using steady-state and time-resolved spectroscopies, combined with nonadiabatic dynamics simulations. Upon visible excitation (λ > 350 nm), rapid (sub-100 fs) internal conversion to S1 leads to the characteristic BODIPY emission aro...
M. Sapunar, I. Antol, Vedran Brusar et al.· Physical Chemistry, Chemical...· 0 citations
Cis-stilbene exhibits ultrafast excited-state dynamics in solution, where photoisomerization and photocyclization compete on the picosecond timescale and are strongly influenced by solvent polarity. Despite extensive experimental studies, the molecular-level mechanism by which solvent environments control nonadiabatic...
Yusuke Minegishi, Satoi Wada, Takuro Tsutsumi et al.· Journal of Chemical Physics· 0 citations
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