The Mechanisms of Strong-Field Control of Chemical Reactivity Using Tailored Laser Pulses

Moore, Noel P.; Menkir, Getahun; Markevitch, Alexei N.; Graham, Paul; Levis, Robert J.

doi:10.1021/bk-2002-0821.ch014

Cited by 10 publications

(10 citation statements)

References 1 publication

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“…However, it is well-known that this molecule can form an intramolecular charge-transfer complex due to −NH 2 and NO 2 functional groups combined at the para-position of the aromatic ring, which would play an important role in the photoionization process. Similar results have been observed for an intramolecular charge-transfer molecule of p -nitroaniline, in which fragmentation has been reported to be more significant at higher pulse energies (0.1 → 0.6 mJ) and longer pulse widths (0.1 → 5 ps) at 790 nm …”

Section: Resultssupporting

confidence: 84%

Determination of Pesticides by Gas Chromatography Combined with Mass Spectrometry Using Femtosecond Lasers Emitting at 267, 400, and 800 nm as the Ionization Source

Yang

Imasaka

2018

Anal. Chem.

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A standard sample mixture containing 51 pesticides was separated by gas chromatography (GC), and the constituents were identified by mass spectrometry (MS) using femtosecond lasers emitting at 267, 400, and 800 nm as the ionization source. A two-dimensional display of the GC/MS was successfully used for the determination of these compounds. A molecular ion was observed for 38 of the compounds at 267 nm and for 30 of the compounds at 800 nm, in contrast to 27 among 50 compounds when electron ionization was used. These results suggest that the ultraviolet laser is superior to the near-infrared laser for molecular weight determinations and for a more reliable analysis of these compounds. In order to study the conditions for optimal ionization, the experimental data were examined using the spectral properties (i.e., the excitation and ionization energies and absorption spectra for the neutral and ionized species) obtained by quantum chemical calculations. A few molecules remained unexplained by the currently reported rules, requiring additional rules for developing a full understanding of the femtosecond ionization process. The pesticides in the homogenized matrix obtained from kabosu ( citrus sphaerocarpa) were measured using lasers emitting at 267 and 800 nm. The pesticides were clearly separated and measured on the two-dimensional display, especially for the data measured at 267 nm, suggesting that this technique would have potential for use in the practical trace analysis of the pesticides in the environment.

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Section: Resultssupporting

confidence: 84%

Determination of Pesticides by Gas Chromatography Combined with Mass Spectrometry Using Femtosecond Lasers Emitting at 267, 400, and 800 nm as the Ionization Source

Yang

Imasaka

2018

Anal. Chem.

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“…From this a productive and systematic series of studies on strong field induced transitions and manipulations of organic molecules emerged (e.g. Levis et al (2001), Moore et al (2002), Markevitch et al (2003Markevitch et al ( , 2004). Similar studies were reported by Harada et al (2001) and (2003).…”

Section: Femtochemistry Optimal Control and Strong Laser Fieldsmentioning

confidence: 99%

Ultrafast dynamics in isolated molecules and molecular clusters

2006

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During the past decade the understanding of photo-induced ultrafast dynamics in molecular systems has improved at an unforeseen speed and a wealth of detailed insight into the fundamental processes has been obtained. This review summarizes our present knowledge on ultrafast dynamics in isolated molecules and molecular clusters evolving after excitation with femtosecond pulses as studied by pump-probe analysis in real time. Experimental tools and methods as well as theoretical models are described which have been developed to glean information on primary, ultrafast processes in photophysics, photochemistry and photobiology. The relevant processes are explained by way of example-from wave packet dynamics in systems with a few atoms all the way to internal conversion via conical intersections in bio-chromophores. A systematic overview on characteristic systems follows, starting with diatomic and including larger organic molecules as well as various types of molecular clusters, such as micro-solvated chromophore molecules. For conciseness the focus is on molecular systems which remain unperturbed by the laser pulses-apart from the excitation and detection processes as such. Thus, only some aspects of controlling and manipulating molecular reactions by shaped and/or very intense laser pulses are discussed briefly for particularly instructive examples, illustrating the perspectives of this prospering field. The material presented in this review comprises some prototypical examples from earlier pioneering work but emphasizes studies from recent years and covers the most important and latest developments until January 2006.

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“…These include schemes employing low lying resonances to maximize fluorescence from a dye molecule in solution, generation of specific photochemical fragments from organometallics , and alkali clusters, maximization of stimulated Raman signal from methanol in solution, and the optimization of coherent antistokes Raman emission . Most recently, shaped, strong field laser pulses have been employed to enable the control of photodissociation processes in organic molecules. , The combination of closed-loop operations with strong field laser control has opened the door to the ready control of chemically interesting processes.…”

Section: Introductionmentioning

confidence: 99%

Closing the Loop on Bond Selective Chemistry Using Tailored Strong Field Laser Pulses

2002

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Strong field, closed-loop control of gas-phase photochemical reactivity is the focus of this article. The control of chemical reactivity is now possible using tailored laser pulses to circumvent previous laser bandwidth limitations. As an illustration of this capability, ketone rearrangements and dissociation reactions are considered. To introduce the experiments we discuss both optimal control theory (OCT) and optimal control experiments (OCE) with an emphasis on closed-loop control methods using near-infrared fs pulses. Because the experiments are in the strong field regime, we present the current state of the understanding of the electronic and nuclear photophysical processes that occur when polyatomic molecules are subjected to laser intensities ranging between 10 13 and 10 15 W cm -2 . Photoelectron spectroscopy measurements are presented that begin to elucidate the control mechanisms. These delineate the order of the multiphoton process, the presence of transient shifting of excited electronic state energies (on the order of 5 eV), and the phenomena of lifetime broadening of electronic states. Recent experiments probing the energy partitioning to nuclear modes are presented with an emphasis on detecting the final kinetic energy of fragment ions. The advances in laser pulse shaping technology slaved to pattern recognition learning algorithms have opened up the prospect of studying the dynamics and chemical manipulation of virtually any system that can be introduced into the closed-loop apparatus. Rather than operating under the limitation of finding the molecule to suit the laser capabilities, the closed-loop learning control procedure operating in the strong field regime now makes it possible to merely tailor the control laser to meet the molecule's dynamical capabilities in keeping with the chemical objectives. The prospects are very bright for exploring chemical reactivity with these tools.

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The Mechanisms of Strong-Field Control of Chemical Reactivity Using Tailored Laser Pulses

Cited by 10 publications

References 1 publication

Determination of Pesticides by Gas Chromatography Combined with Mass Spectrometry Using Femtosecond Lasers Emitting at 267, 400, and 800 nm as the Ionization Source

Determination of Pesticides by Gas Chromatography Combined with Mass Spectrometry Using Femtosecond Lasers Emitting at 267, 400, and 800 nm as the Ionization Source

Ultrafast dynamics in isolated molecules and molecular clusters

Closing the Loop on Bond Selective Chemistry Using Tailored Strong Field Laser Pulses

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