X-ray transient absorption spectroscopy by an ultrashort x-ray-laser pulse in a continuous-wave IR field

Abstract

X-ray transient absorption spectra (XTAS) of molecules are theoretically investigated in a femtosecond x-ray pump and continuous wave (CW) infrared (IR)-control scenario. The scheme is exemplified by CO molecule resonantly pumped into carbon and oxygen core-excited 1s→π * states by a weak femtosecond x-ray pulse, while dynamic Stark shifts are induced by the CW IR-control radiation. As a result, significant shoulder structures appear in XTAS showing strong dependence on the phase of IR radiation relative to the envelope of the x-ray pulse. Due to a significant difference in the frequencies of the two pulses, the present XTAS scheme provides much clear interpretation of the dynamic Stark effects as compared to attosecond UV transient absorption scenario. Within suggested two-level model, where the total spectrum is decomposed as incoherent superposition of contributions from different vibrational excitations weighted by the Frank-Condon Factors, all spectral structures can be well identified and interpreted in a good agreement with the full-scale molecular simulations. Well characterized XTAS in the proposed IR-control scheme can be applied for fine phase synchronization between IR and x-ray pulses, highly demanded in the modern experiments at x-ray free-electron lasers.

Investigation of the laser-induced lineshape change in attosecond transient absorption spectra by employing a time-dependent generalized Floquet approach

“…In the past decades, the advent of attosecond pulses offers a powerful tool to trace the electronic response in atoms and molecules in atoms [1][2][3][4][5][6][7][8][9][10][11], molecules [12][13][14][15][16][17][18][19][20] and solid targets [21][22][23][24][25][26][27] in the natural timescale of electronic dynamics [28][29][30][31][32]. An attosecond extreme ultraviolet (XUV) pulse synchronized with an infrared (IR) laser pulse gives rise to a transient absorption measurement, so-called attosecond transient absorption spectroscopy (ATAS), to investigate the IR-laser-driven electronic dynamics at the sub-optical-cycle scale, with the temporal resolution indirectly accessed through the highly controlled time delay between pulses.…”

Macroscopic transient absorption in a V-type three-level system

“…Typically, a triggering pump initializes the processes and a subsequent probe takes snapshots of the ensuring evolutions [2][3][4]. While for inverted arrival order, the following pump manipulates the polarization response preexcited by the probe and leaves fingerprint to its transmitted spectrum [5][6][7][8][9][10][11][12][13][14]. 4 Authors to whom any correspondence should be addressed.…”

Resonant Auger Scattering by Attosecond X-Ray Pulses

“…Our theoretical approach is based on a fully quantum time-dependent wave-packet technique, which has been comprehensively described in previous works. [29][30][31][32][33][34][35][36][37][38] The nuclear wave packet 𝛹𝛾(𝑡) is associated with the electronic state |𝛾⟩ = |G⟩, |N⟩, |F⟩, and 𝜀 is the energy of a released electron.…”