Stockholms universitet

Deependra JadounDoktorand

Forskningsprojekt

Publikationer

I urval från Stockholms universitets publikationsdatabas

  • Capturing fingerprints of conical intersection

    2021. Deependra Jadoun, Mahesh Gudem, Markus Kowalewski. Structural Dynamics 8 (3)

    Artikel

    Many recent experimental ultrafast spectroscopy studies have hinted at non-adiabatic dynamics indicating the existence of conical intersections, but their direct observation remains a challenge. The rapid change of the energy gap between the electronic states complicated their observation by requiring bandwidths of several electron volts. In this manuscript, we propose to use the combined information of different x-ray pump-probe techniques to identify the conical intersection. We theoretically study the conical intersection in pyrrole using transient x-ray absorption, time-resolved x-ray spontaneous emission, and linear off-resonant Raman spectroscopy to gather evidence of the curve crossing.

    Läs mer om Capturing fingerprints of conical intersection
  • Time-Resolved Photoelectron Spectroscopy of Conical Intersections with Attosecond Pulse Trains

    2021. Deependra Jadoun, Markus Kowalewski. Journal of Physical Chemistry Letters 12 (33), 8103-8108

    Artikel

    Conical Intersections (CIs), which are believed to be ubiquitous in molecular and biological systems, open up ultrafast nonradiative decay channels. A superposition of electronic states is created when a molecule passes through a CI and the nuclear wave packet branches. The resulting electronic coherence can be considered a unique signature of the CI. The involved electronic states can be resolved in the energy domain with photoelectron spectroscopy using a femtosecond pulse as a probe. However, the observation of the created electronic coherence in the time domain requires probe pulses with several electron volts of bandwidth. Attosecond pulses can probe the electronic coherence but are unable to resolve the involved electronic states. In this Letter, we propose to address this restriction by using time- resolved photoelectron spectroscopy with an attosecond pulse train as a probe. We theoretically demonstrate that the resulting photoelectron spectrum may yield energy resolution as well as the information on the created coherences in the time domain.

    Läs mer om Time-Resolved Photoelectron Spectroscopy of Conical Intersections with Attosecond Pulse Trains
  • Probing nonadiabatic dynamics with attosecond pulse trains and soft x-ray Raman spectroscopy

    2022. Lorenzo Restaino, Deependra Jadoun, Markus Kowalewski. Structural Dynamics 9 (3)

    Artikel

    Linear off-resonant x-ray Raman techniques are capable of detecting the ultrafast electronic coherences generated when a photoexcited wave packet passes through a conical intersection. A hybrid femtosecond or attosecond probe pulse is employed to excite the system and stimulate the emission of the signal photon, where both fields are components of a hybrid pulse scheme. In this paper, we investigate how attosecond pulse trains, as provided by high-harmonic generation processes, perform as probe pulses in the framework of this spectroscopic technique, instead of single Gaussian pulses. We explore different combination schemes for the probe pulse as well as the impact of parameters of the pulse trains on the signals. Furthermore, we show how Raman selection rules and symmetry consideration affect the spectroscopic signal, and we discuss the importance of vibrational contributions to the overall signal. We use two different model systems, representing molecules of different symmetries, and quantum dynamics simulations to study the difference in the spectra. The results suggest that such pulse trains are well suited to capture the key features associated with the electronic coherence.

    Läs mer om Probing nonadiabatic dynamics with attosecond pulse trains and soft x-ray Raman spectroscopy

Visa alla publikationer av Deependra Jadoun vid Stockholms universitet