Laser-induced excitation and ionization of a confined hydrogen atom in an exponential-cosine-screened Coulomb potential

The energy spectra of spherically confined hydrogen atom embedded in an exponential-cosine-screened Coulomb potential is worked out by using the Bernstein-polynomial method. The interaction of short laser pulses in the femtosecond range with the system is studied in detail. The effect of shape of laser pulse, confinement radius, Debye screening length as well as different laser parameters on the dynamics of the system has been explored and analyzed.

Figure 1

Bar diagram: Energy difference of first two states with respect to Debye screening length ${\lambda }_D$ for $r_0=10$ and 50 a.u.

Figure 2

Bar diagram: Energy difference of ground and first-ionized state with respect to Debye screening length ${\lambda }_D$ for $r_0=10$ and 50 a.u.

Figure 3

Time variation of various probabilities. The probabilities in panels (e) and (f) are plotted on a logarithmic scale. The legend in panel (c) applies to all panels and $r_0$ values are as mentioned in respective panels. Laser parameters are $E_0=0.01$ a.u., ${\omega }_0=E_{2p}-E_{1s}$ a.u., and $t_p=2067$ a.u. ($\approx 50$ fs).

Figure 4

Variation of ionization probabilities with respect to $E_0$ for ${sin}^2$ and square pulses. $r_0$ and ${\lambda }_D$ are as mentioned in each panel. Other laser parameters are ${\omega }_0=E_{2p}-E_{1s}$ a.u. and $t_p=2067$ a.u. The insets show the corresponding variation of survival probability for a small range of $E_0$ values.

Figure 5

Variation of various probabilities with respect to $w_0$ for $r_0$ values as mentioned in respective panels. The probabilities in panels (e) and (f) are plotted on a logarithmic scale. The legend in panel (a) applies to all panels. Other laser parameters are $E_0=0.01$ a.u. and $t_p=2067$ a.u.

Figure 6

Variation of transition probabilities with respect to $w_0$ for $r_0=50$ a.u. The legend in panel (b) applies to both panels. Other laser parameters are $E_0=0.05$ a.u. and $t_p=2067$ a.u.

Figure 7

Bar diagram: Variation of various probabilities with respect to duration of the pulse ($t_p$) for ${sin}^2$ and square pulses. Legend 1: $1s$ (square), 2: $1s$ (${sin}^2$), 3: excitation (square), 4: excitation (${sin}^2$), 5: ionization (square), 6: ionization (${sin}^2$). Other parameters are $r_0=50$ a.u., ${\lambda }_D=10$ a.u., $E_0=0.5$ a.u., and ${\omega }_0=E_{2p}-E_{1s}$ a.u.