Ultrafast Excitation of an Inner-Shell Electron by Laser-Induced Electron Recollision

Abstract

Extreme ultraviolet attosecond pulses, generated by a process known as laser-induced electron recollision, are a key ingredient for attosecond metrology, providing a tool to precisely initiate and probe subfemtosecond dynamics in atoms, molecules, and solids. However, extending attosecond metrology to scrutinize the dynamics of the inner-shell electrons is a challenge, that is because of the lower efficiency in generating the required soft x-ray (ℏω>300 eV) attosecond bursts. A way around this problem is to use the recolliding electron to directly initiate the desired inner-shell process, instead of using the currently low flux x-ray attosecond sources. Such an excitation process occurs in a subfemtosecond time scale, and may provide the necessary "pump" step in a pump-probe experiment. Here we used a few cycle infrared (λ_{0}≈1800 nm) source and observed direct evidence for inner-shell excitations through the laser-induced electron recollision process. It is the first step toward time-resolved core-hole studies in the keV energy range with subfemtosecond time resolution.

Proposal for strong field physics simulation by means of optical waveguide

“…The interaction of atoms and molecules with intense lasers is a key for a rich set of physical phenomena associated with attosecond physics processes such as high harmonic generation [1][2][3][4] (HHG), above threshold ionization [5] (ATI), laser induced diffraction imaging [6] (LIED), laser induced innershell excitation [7,8] and steering electrons in molecules [9]. The simple-man model, known also as the three-step-model [10,11] is a good starting point to gain an insight into these high-field processes.…”

Unexpected Sensitivity of Nitrogen Ions Superradiant Emission on Pump Laser Wavelength and Duration

“…Only a linear or slightly elliptical laser field can force an ionized electron to return to the molecular ion with a significant kinetic energy. The resulting recollision is at the origin of many physical processes such as HHG [15,16], nonsequential double ionization [17], molecular fragmentation [18], formation of high-order Rydberg atoms [19], and inner-shell electronic excitation of molecules [20].…”

Superelastic rescattering in single ionization of helium in strong laser fields

“…Depending on the energy that the electron transfers, a second electron may be directly knocked out, resulting in nonsequential double ionization [7,[12][13][14], or be pumped to some excited states which will be subsequently tunneling ionized by the field [15,16]. Recently, Deng et al further demonstrated inner-shell excitation by rescattering followed by x-ray emission [17]. In molecules, the rescattering electron may excite the parent molecular ion to repulsive states, thus initiating molecular dissociation or Coulomb explosion [18][19][20][21].…”