TY  - JOUR
A1  - Liu, Ji-Cai
A1  - Vaz da Cruz, Vinicius
A1  - Polyutov, Sergey
A1  - Föhlisch, Alexander
T1  - Recoil-induced dissociation in hard-x-ray photoionization
JF  - Physical review : A, Atomic, molecular, and optical physics
N2  - We predict the recoil-induced molecular dissociation in hard-x-ray photoionization. The recoil effect is caused by electronic and photon momentum exchange with the molecule. We show the strong role of relativistic effects for the studied molecular fragmentation. The recoil-induced fragmentation of the molecule is caused by elongation of the bond due to the vibrational recoil effect and because of the centrifugal force caused by the rotational recoil. The calculations of the x-ray photoelectron spectra of the H-2 and NO molecules show that the predicted effects can be observed in high-energy synchrotrons like SOLEIL, SPring-8, PETRA, and XFEL SACLA. The relativistic effect enhances the recoil momentum transfer and makes it strongly sensitive to the direction of ejection of the fast photoelectron with respect to the photon momentum.
Y1  - 2019
U6  - https://doi.org/10.1103/PhysRevA.100.053408
SN  - 2469-9926
SN  - 2469-9934
VL  - 100
IS  - 5
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Liu, Ji-Cai
A1  - Ignatova, Nina
A1  - Kimberg, Victor
A1  - Krasnov, Pavel
A1  - Föhlisch, Alexander
A1  - Simon, Marc
A1  - Gel'mukhanov, Faris
T1  - Time-resolved study of recoil-induced rotation by X-ray pump - X-ray probe spectroscopy
JF  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - Modern stationary X-ray spectroscopy is unable to resolve rotational structure. 
In the present paper, we propose to use time-resolved two color X-ray pump-probe spectroscopy with picosecond resolution for real-time monitoring of the rotational dynamics induced by the recoil effect. 
The proposed technique consists of two steps. 
The first short pump X-ray pulse ionizes the valence electron, which transfers angular momentum to the molecule. 
The second time-delayed short probe X-ray pulse resonantly excites a 1s electron to the created valence hole. 

Due to the recoil-induced angular momentum the molecule rotates and changes the orientation of transition dipole moment of core-excitation with respect to the transition dipole moment of the valence ionization, which results in a temporal modulation of the probe X-ray absorption as a function of the delay time between the pulses. 
We developed an accurate theory of the X-ray pump-probe spectroscopy of the recoil-induced rotation and study how the energy of the photoelectron and thermal dephasing affect the structure of the time-dependent X-ray absorption using the CO molecule as a case-study. 
We also discuss the feasibility of experimental observation of our theoretical findings, opening new perspectives in studies of molecular rotational dynamics.
Y1  - 2022
U6  - https://doi.org/10.1039/d1cp05000a
SN  - 1463-9076
SN  - 1463-9084
VL  - 24
IS  - 11
SP  - 6627
EP  - 6638
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  -