Mapping the Dissociative Ionization Dynamics of Molecular Nitrogen with Attosecond Time Resolution

Abstract

Studying the interaction of molecular nitrogen with extreme ultraviolet (XUV) radiation is of prime importance to understand radiation-induced processes occurring in Earth’s upper atmosphere. In particular, photoinduced dissociation dynamics involving excited states of N2+ leads to N and N+ atomic species that are relevant in atmospheric photochemical processes. However, tracking the relaxation dynamics of highly excited states of N2+ is difficult to achieve, and its theoretical modeling is notoriously complex. Here, we report on an experimental and theoretical investigation of the dissociation dynamics of N2+ induced by isolated attosecond XUV pulses in combination with few-optical-cycle near-infrared/visible (NIR/VIS) pulses. The momentum distribution of the produced N+ fragments is measured as a function of pump-probe delay with subfemtosecond resolution using a velocity map imaging spectrometer. The time-dependent measurements reveal the presence of NIR/VIS-induced transitions between N2+ states together with an interference pattern that carries the signature of the potential energy curves activated by the XUV pulse. We show that the subfemtosecond characterization of the interference pattern is essential for a semiquantitative determination of the repulsive part of these curves

Phonocatalysis. An ab initio simulation experiment

“…[50][51][52][53] From the experiments of femtosecond laser-induced oxidation of CO on Ru(100), the CO oxidation driven by an electronic excitation (fast response) and the CO desorption coupled with phonons (slow response) were distinguished. 50 Also, the two-step mechanism of the CO desorption on Ru(0001) has been demonstrated.…”

Mapping and controlling ultrafast dynamics of highly excited H2 molecules by VUV-IR pump-probe schemes

“…Recent studies showed how femtosecond VUV and XUV radiation can be used to reveal transient nuclear and electron dynamics in diatomic molecules [8][9][10][11][12] as well as in more complex molecular systems [13,14]. To probe such dynamics, the majority of the pump-probe-style experiments accomplished to date utilize not only pairs of XUV-IR pulses [8,[15][16][17][18], but also a combination of VUV-XUV pulses [19][20][21][22].…”

Core-level attosecond transient absorption spectroscopy of laser-dressed solid films of Si and Zr

“…Theoretically, it is described as the manipulation of 38 the electron-wave-packet dynamics of the unoccupied and 39 occupied electronic states of the material [4]. 40 For atomic and molecular gases such as argon [5], neon 41 [6], helium [7,8], N 2 [9], Br 2 [10], and hydrocarbons [11], probe [3,[12][13][14] were the subject of fewer studies. Besides 47 the change in absorption, Stark shift in He [15] and Ar [5], 48 Rabi oscillations [16] in Ne, line broadening [5], and quantum 49 beats [17,18] were recognized in the recorded XUV or photo-50 electron spectra.…”