Tunneling ionization, a fascinating quantum phenomenon, has played the key role in the development of attosecond physics. Upon absorption of a few tens of photons, tunneling ionization creates ions in different excited states and even enables the formation of population inversion between ionic states. However, the underlying physics is still being debated. Here, we demonstrate a significant enhancement in the efficiency of multiphoton excitation when ionization of neutral molecules and resonant excitation of ions coexist in strong laser fields. It facilitates the dramatic increase in population inversion and lasing radiation in N_{2}^{+} around 1000 nm pump wavelength. Utilizing the ionization-coupling theory, we discover that the synergistic interplay between tunneling ionization and multiphoton excitation enables the ionic coherence to be maximized by phase locking of the periodically created ionic dipoles and consistently maintain an optimal phase for the follow-up photoexcitation. This Letter provides new insights into the photoexcitation mechanism of ions in strong laser fields and opens up a route for optimizing ionic lasing radiations.
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http://dx.doi.org/10.1103/PhysRevLett.133.113201 | DOI Listing |
This Letter describes the first, to the best of our knowledge, demonstration of a velocity measurement by nitric oxide ionization induced flow tagging and imaging (NiiFTI) of a high-enthalpy hypersonic flow utilizing naturally formed nitric oxide. The measurements were conducted in the hypervelocity expansion tunnel (HXT) at Texas A&M University in Mach 8.5 and Mach 10 flows near an ogive test article.
View Article and Find Full Text PDFJ Phys Chem Lett
December 2024
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123, P. R. China.
Alkali element doping has significant physical implications for two-dimensional materials, primarily by tuning the electronic structure and carrier concentration. It can enhance interface electronic interactions, providing opportunities for effective charge transfer at metal-organic interfaces. In this work, we investigated the effects of gradually increasing the level of K doping on the lattice structure and electronic properties of an organometallic coordinated Kagome lattice on a Ag(111) surface.
View Article and Find Full Text PDFPhys Chem Chem Phys
December 2024
JEOL Ltd, Akishima, Tokyo, 196-8558, Japan.
The McLafferty rearrangement (McLR) of the methyl valerate molecular ion has been comprehensively studied from the standpoints of the timescale for the keto-enol transformation and the change of the configuration of intermediates and transition state (TS), using mass spectrometry with electron ionization, strong-field tunnel ionization and collision-induced dissociation methods, and the global reaction route mapping (GRRM) program with quantum chemical calculations (QCCs). The timescales estimated from mass spectrometric results suggested that the McLR starts at 100 fs after ionization and is completed at least within 100 ns in the ion source. Whereas the timescales are consistent with a stepwise mechanism of fast (100 fs) and slow (10 ps) steps presented by Stamm , the QCCs put forth the possibility that an unanticipated, rapid, concerted process may be involved in completing the McLR reaction.
View Article and Find Full Text PDFJ Phys Chem A
November 2024
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0309, United States.
Characterization of the structural and electron transport properties of single chiral molecules provides critical insights into the interplay between their electronic structure and electrochemical environments, providing broader implications given the significance of molecular chirality in chiroptical applications and pharmaceutical sciences. Here, we examined the topographic and electronic features of a recently developed chiral molecule, B,N-embedded double hetero[7]helicene, at the edge of Cu(100)-supported NaCl thin film with scanning tunneling microscopy and spectroscopy. An electron transport energy gap of 3.
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