Ultrafast structural and isomerization dynamics in the Rydberg-exited Quadricyclane: Norbornadiene system

Abstract

The quadricyclane-norbornadiene system is an important model for the isomerization dynamics between highly strained molecules. In a breakthrough observation for a polyatomic molecular system of that complexity, we follow the photoionization from Rydberg states in the time-domain to derive a measure for the time-dependent structural dynamics and the time-evolving structural dispersion even while the molecule is crossing electronic surfaces. The photoexcitation to the 3s and 3p Rydberg states deposits significant amounts of energy into vibrational motions. We observe the formation and evolution of the vibrational wavepacket on the Rydberg surface and the internal conversion from the 3p Rydberg states to the 3s state. In that state, quadricyclane isomerizes to norbornadiene with a time constant of τ(2) = 136(45) fs. The lifetime of the 3p Rydberg state in quadricyclane is τ(1) = 320(31) and the lifetime of the 3s Rydberg state in norbornadiene is τ(3) = 394(32).

Non-intrusive detection of combustion intermediates by photoionization via Rydberg states and microwave backscattering

“…13,14,15,16 Because the method can be implemented with ultrafast time resolution, it is also possible to apply the photoionization via Rydberg states to probe molecular structure and dynamics in highly energetic molecules. 17,18,19,20,21 The combination of high sensitivity to the molecular structure, insensitivity to vibrational motion, and applicability to large molecules makes it attractive to suggest photoionization through Rydberg states as a tool for detection of combustion intermediates. 4 We note that the insensitivity of Rydberg spectra to vibrational motion is based on an adiabatic approximation.…”

Self-interaction corrected density functional calculations of molecular Rydberg states

“…3 This has led to the recent development of spectroscopic tools that use Rydberg states for the identification of molecular structures and possibly of molecules. [4][5][6][7][8][9][10] For many practical applications, the determination of molecular structures remains an important challenge. Examples include situations when samples are extremely dilute or where rapid throughput is of the essence.…”

Photodeactivation paths in norbornadiene

“…After depletion of the population from the R 1 to the V 2 state, a second pathway merges with the path started on the V 2 state . Very recently, the lifetime of the 3s Rydberg state in norbornadiene was reported as 394 fs from time‐resolved photo‐electron spectroscopy experiments . Although it is well known that the interpretation of the data and unveiling of the molecular transformations experienced by a photoactive molecule require a strong synergy between the experiment and theory, proposed pathways for norbornadiene deactivation have only been guessed on the basis of spectroscopic data as the potential energy surfaces of excited states and postulated conical intersections were not available from the quantum‐chemical calculations.…”

“…[16] Very recently, the lifetime of the 3s Rydberg state in norbornadiene was reported as 394 fs from time-resolved photo-electron spectroscopy experiments. [17] Although it is well known that the interpretation of the data I. Antol Division of Organic Chemistry and Biochemistry, Ruder Bosˇković Institute, P.O.B. 180, HR-10002, Zagreb, Croatia E-mail: iantol@emma.irb.hr and unveiling of the molecular transformations experienced by a photoactive molecule require a strong synergy between the experiment and theory, [18] proposed pathways for norbornadiene deactivation have only been guessed on the basis of spectroscopic data [5] as the potential energy surfaces of excited states and postulated conical intersections were not available from the quantum-chemical calculations.…”