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We use tailored femtosecond laser pulses to induce and control coherent electronic excitation
of molecular systems in gas, solid, and liquid phases. One of the significant applications of
coherent electronic excitation is towards quantum information. We search for ideal quantum
systems in the form of molecular complexes with long-lived levels isolated from the
environment to form quantum bits as key building blocks for advanced quantum technologies.
Lanthanides are particularly promising with respect to possible applications in quantum-based
information storage. Recently, we have reported our observation on long-lived electronic
coherences modulated by vibrational dynamics in lanthanide (Nd3+) molecular complexes for
the excitation from the ground state 4
I9/2 to the electronically excited manifold of 4F5/2 and 2H9/2
states at room temperature [1] which is a promising result towards building molecular qubits.
For further investigation to control and manipulate the electronic coherence we use spectrally
phase-shaped femtosecond laser pulses. To this end, we use phase-locked IR femtosecond
coherent pairs of pulses and fluorescence detection under a confocal microscope.
Another application is towards controlling molecular chirality and developing new methods
for efficiently detecting molecular chirality in the gas and liquid phase. Chiral molecules offer
opportunities for the exquisite control of electron and spin transport due to extraordinary
optical, electronic, and magnetic properties that depend on the structure’s handedness, making
them potential candidates for future quantum information applications. However, as a first step
to differentiate between the two enantiomers of a chiral molecule and to control the electronic
properties, we measure Circular Dichroism in ion yield (CDIY). It arises due to the difference
in absorption of left and right circularly polarised light. The difference in absorption can also
be mapped to the difference in ionization of the enantiomers and is known as CD in ion yield
[2,3]. We use our home-built Time of Flight (ToF) mass spectrometer with our recently
established twin peak [4] measurement setup and coherent control technique to manipulate the
chirality effect. We have observed a huge enhancement of anisotropy (up to ~10%) for 3-
methylcyclopentanone using resonance-enhanced multi-photon ionization (REMPI). Recently,
we are developing new experimental techniques for detecting molecular chirality in the liquid
phase using micron-thick liquid samples into a vacuum using synchrotron and X-ray free
electron laser.
References: [1] J. Ghosh, et al., ChemPhysChem, 2023, 24, e202300001. [2] U. Boesl and A.
Bornschlegl, ChemPhysChem, 7, 2085, 2006 [3] H. G. Breunig et al., ChemPhysChem, 10,
1199, 2009 [4] T. Ring et al., Rev. Sci. Instrum., 92, 033001, 2021. |