Real-time calibration of nuclear velocities in the dissociation of heteronuclear molecules in strong laser fields

Abstract

We design a strategy for the real-time calibration of nuclear velocities in ultrafast molecular reactions in strong laser fields by simulating the four-dimensional time-dependent Schr\"odinger equation. Taking $\mathrm{H}{\mathrm{D}}^{+}$ as the prototype, an attosecond pump pulse initiates the molecular dissociation, and the other time-delayed attosecond probe pulse, polarized in the plane perpendicular to the molecular axis, ionizes the dissociating $\mathrm{H}{\mathrm{D}}^{+}$. During the dissociation, two nuclei with different masses acquire different velocities, which imprint on the photoelectron kicked off by the probe pulse. The expected photoelectron momentum along the molecular axis can be used to precisely calibrate instantaneous nuclear velocities at ionization. This strategy works widely in general heteronuclear molecules and paves the way for making high-definition molecular movies.