AUTHOR=Zhang Rong , Hu Jin-Wei , Han Yong-Chang , Fu Bina , Shundalau Maksim 

TITLE=Steering thermal photoassociation of magnesium atoms by two time-delayed femtosecond laser pulses

JOURNAL=Frontiers in Physics

VOLUME=Volume 11 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2023.1114719

DOI=10.3389/fphy.2023.1114719

ISSN=2296-424X

ABSTRACT=By solving the full-dimensional time-dependent Schr\"{o}dinger equation with the thermal-random-phase wavepacket method, we investigate the photoassociation (PA) process of hot ($1000$ K) magnesium atoms induced by two time-delayed femtosecond laser pulses. Driven by the 840 nm femtosecond laser pulses, the Mg$_{2}$ molecules can be formed on the four excited states, $(1)^{1}\Pi_{g}$, $(1)^{1}\Pi_{u}$, $(2)^{1}\Pi_{u}$, and $(2)^{1}\Sigma^{+}_{u}$, from the initial electronic ground state $X^{1}\Sigma^{+}_{g}$. It is found that the three-photon couplings between $X^{1}\Sigma^{+}_{g}$ and the three ungerade states ($(1)^{1}\Pi_{u}$, $(2)^{1}\Pi_{u}$, and $(2)^{1}\Sigma^{+}_{u}$) play dominant roles in the population transfer process. By scanning the pulse duration $\tau$ from 50 to 200 fs, and varying the delay time $\delta t_{0}$ from 0 to $2 \tau$ fs, we find that the final PA population is strongly dependent on the two parameters. For a given $\delta t_{0}$, the parameter $\tau$ can induce a significant variation ($2\sim6.8$ times) for the final PA population transfer, and for a given $\tau$, one can also obtain a significant variation ($2.7\sim3.5$ times) of the final PA population by varying $\delta t_{0}$. Additionally, the dynamics of the coherently vibrational wavepackets of the four excited states are also influenced by the two parameters.