Controlling Photodetachment of Hydrogen Anion By Chirped Few-Cycle Laser Pulses

Few-cycle pulses are effective tools to probe ultrashort atomic ionization processes [1–6] by varying the pulse parameters. For the case of photodetachment of H− of interest here, most of the work done has been centered on revealing the sensitivity of the angular distribution of the detached electrons to the wavelength, intensity, duration and carrier-envelope phase [1,2]; there are only few studies on chirp effect [4]. Solving the time-dependent Schrödinger equation, the study [4] used intense and high-frequency pulses to report on low-energy electrons produced by Raman processes in the energy distribution. Here, within the strong-field approximation (SFA) framework used in [2] valid for both perturbative and nonperturbative regimes, we revisit the nonlinear multiphoton process of photodetachment of H- using intense but low-frequency few-cycle chirped linearly-polarized pulses. We present a study for the directional control of the momentum distribution of the detached electron. Our chirped field is parameterized as in [4], but in a more realistic way to include the increase in pulse duration and the decrease in pulse intensity induced by the chirp. Preliminary results for a single-cycle Gaussian envelope indicate a strong chirp effect when the dimensionless chirp rate varies from 1 to 2. As expected, this effect vanishes with increasing pulse length. The zero-net-force exerted on the H- requirement is also discussed. These findings introduce an alternative approach for chirpmetry, offering valuable insights into ultrafast laser pulse manipulation and control of electron dynamics in photodetachment processes.