Asymmetric fragmentation of D$_{2}$H$^{+}$ by intense ultrashort laser pulses*

The triatomic hydrogen molecular ion is a fundamentally important molecule as it plays a key role in interstellar and plasma chemistry. More importantly for intense laser studies, it is seen as the stepping stone to better understanding the laser-driven dynamics of polyatomic molecules. Recently, we have made a breakthrough by performing the first studies on H$_{3}^{+}$ and D$_{3}^{+}$ fragmentation in ultrashort intense laser pulses using coincidence 3D momentum imaging. Studying the D$_{2}$H$^{+}$ isotopologue, we now find exciting differences between equivalent breakup channels. For example, for 7\,fs, 790\,nm pulses the 2-body single ionization channel, H$^{+}$+D$_{2}^{+}$, is a factor of 5 larger than its counterpart channel, D$^{+}$+HD$^{+}$. Wavepacket propagation calculations are needed to determine the precise origin of the effect.