Quantum coherent control of H3+ formation in strong fields

Abstract

Quantum coherent control (QCC) has been successfully demonstrated experimentally and theoretically for two-and threephoton optical excitation of atoms and molecules. Here, we explore QCC using spectral phase functions with a single spectral phase step for controlling the yield of H 3 + from methanol under strong laser field excitation. We observe a significant and systematic enhanced production of H 3 + when a negative 3 /4 π phase step is applied near the low energy region of the laser spectrum and when a positive 3 /4 π phase step is applied near the high energy region of the laser spectrum. In some cases, most notably the HCO + fragment, we found the enhancement exceeded the yield measured for transform limited pulses. The observation of enhanced yield is surprising and far from the QCC prediction of yield suppression. The observed QCC enhancement implies an underlying strong field process responsible for polyatomic fragmentation controllable by easy to reproduce shaped pulses.Published under license by AIP Publishing. https://doi.

Control of electron recollision and molecular nonsequential double ionization

“…3(b). Furthermore, our findings are consistent with enhanced H 3 + formation from methanol observed under similar experimental conditions 41 . Further confirmation using shorter pulses, where the greater bandwidth will allow a greater frequency change, will be valuable.…”

“…6). These types of pulses, with a positive or negative ¾π phase step, were employed in connection with control of the strongfield fragmentation of methanol 41 . The time-dependent intensity I(t) of the pair of shaped pulses used to obtain the TOF spectra shown in Fig.…”

Urknall der Chemie

“…Dieser wird im Weltraum in interstellaren Wolken, in Gasriesen wie dem Jupiter sowie in der Ionosphäre der Erde nachgewiesen. Die Synthese bei irdischen Bedingungen ist nicht ganz so einfach, aber die Arbeitsgruppe von Marcos Dantus an der University of Michigan in East Lansing, USA, hat ein Verfahren optimiert, das mit genau ausgezirkelten, Femtosekunden dauernden Laserpulsen die drei Wasserstoffatome aus organischen Molekülen wie Methanol oder Ethanol herausschlägt und zu der dreieckigen, hochreaktiven Verbindung vereinigt .…”

Dawn of Chemistry

“…Comparing these pulse shapes to acoustic tunes, the researchers identified several tunes that encourage the formation of trihydrogen and one that suppresses it. 3 As the source of the hydrogen atoms, alcohols have proven useful. Dantus' group has first shown the effect with methanol but now finds that higher alcohols like ethanol work as well.…”