[
{
"id": "authors:6zr12-w7m50",
"collection": "authors",
"collection_id": "6zr12-w7m50",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140102-111659364",
"type": "article",
"title": "Historical perspective on: Femtosecond transition-state spectroscopy of iodine\u2014From strongly bound to repulsive surface dynamics [Volume 161, Issues 4\u20135, 22 September 1989, Pages 297\u2013302]",
"author": [
{
"family_name": "Bowman",
"given_name": "R. M.",
"clpid": "Bowman-R-M"
},
{
"family_name": "Dantus",
"given_name": "M.",
"clpid": "Dantus-M"
},
{
"family_name": "Zewail",
"given_name": "A. H.",
"clpid": "Zewail-A-H"
},
{
"family_name": "Herek",
"given_name": "Jennifer L.",
"clpid": "Herek-J-L"
}
],
"abstract": "Summary by J.L. Herek. Nobel prize-winner: Professor Ahmed Zewail. In the spring of 1990, I was a young liberal arts student soon to graduate from Lawrence University in Wisconsin, dreaming of a career in chemical physics. Thanks to an elective course on applications of lasers in chemistry and physics, which also required a literature study and report, I had found that a revolution in chemical physics was underway, with many groups clamouring to conquer new territory in the study of chemical reactions: the elusive and fleeting transition state. My interest in this emerging field dictated my choices of potential graduate schools, with Caltech and the group of Ahmed Zewail at the top of my list.",
"doi": "10.1016/j.cplett.2013.08.045",
"issn": "0009-2614",
"publisher": "Elsevier",
"publication": "Chemical Physics Letters",
"publication_date": "2013-12-03",
"volume": "589",
"pages": "41-41"
},
{
"id": "authors:7vt67-aqz78",
"collection": "authors",
"collection_id": "7vt67-aqz78",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140102-103501008",
"type": "article",
"title": "Reprint of: Femtosecond transition-state spectroscopy of iodine: From strongly bound to repulsive surface dynamics",
"author": [
{
"family_name": "Bowman",
"given_name": "R. M.",
"clpid": "Bowman-R-M"
},
{
"family_name": "Dantus",
"given_name": "M.",
"clpid": "Dantus-M"
},
{
"family_name": "Zewail",
"given_name": "A. H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "The application of femtosecond transition-state spectroscopy (FTS) to molecular iodine is reported. The real-time motion of wave packets prepared coherently in the bound B state is observed. In addition, the motion is probed near and above the dissociation limit for the reaction: I_2 \u2192 I (^2P_(3/2)) + I\u2217(^2P_(1/2)). FTS measurements of the dynamics on repulsive surfaces are also reported.",
"doi": "10.1016/j.cplett.2013.08.065",
"issn": "0009-2614",
"publisher": "Elsevier",
"publication": "Chemical Physics Letters",
"publication_date": "2013-12-03",
"volume": "589",
"pages": "42-45"
},
{
"id": "authors:hx1m6-kxn78",
"collection": "authors",
"collection_id": "hx1m6-kxn78",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160817-092917194",
"type": "article",
"title": "Introduction: Femtochemistry",
"author": [
{
"family_name": "Dantus",
"given_name": "Marcos",
"clpid": "Dantus-M"
},
{
"family_name": "Zewail",
"given_name": "Ahmed",
"clpid": "Zewail-A-H"
}
],
"abstract": "Only a few years after femtochemistry was first established as a field of research did we witness an explosion of research in all phases of matter and in biological systems. The reason behind this explosion is fundamentals-chemical bonds form and break on the femtosecond time scale, and on this scale of time we can freeze the transition states at configurations never seen before. Even if there is no reactants-to-products transformations - physical changes - one is observing the most elementary of all molecular processes. On a time scale shorter than the vibrational and rotational periods, the ensemble behaves coherently as a single-molecule trajectory.",
"doi": "10.1021/cr020690k",
"issn": "0009-2665",
"publisher": "American Chemical Society",
"publication": "Chemical Reviews",
"publication_date": "2004-04",
"series_number": "4",
"volume": "104",
"issue": "4",
"pages": "1717-1718"
},
{
"id": "authors:1qs5a-62879",
"collection": "authors",
"collection_id": "1qs5a-62879",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160826-104206857",
"type": "article",
"title": "Ultrafast Electron Diffraction. 5. Experimental Time Resolution and Applications",
"author": [
{
"family_name": "Dantus",
"given_name": "Marcos",
"clpid": "Dantus-M"
},
{
"family_name": "Kim",
"given_name": "Scott B.",
"clpid": "Kim-S-B"
},
{
"family_name": "Williamson",
"given_name": "J. Charles",
"clpid": "Williamson-J-C"
},
{
"family_name": "Zewail",
"given_name": "Ahmed H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "This paper, the fifth in a series, is concerned with the experimental description of ultrafast electron diffraction\nand its application to several isolated chemical systems. We present a detailed description of the Caltech apparatus, which consists of a femtosecond laser system, a picosecond electron gun, and a two-dimensional charge-coupled device ( CCD) detection system. We also discuss the analysis of the scattering patterns. Ultrafast diffraction images from several molecules (CCl_4, I_2, CF_3l, C_2F_4I_2) are reported. For our first study of a chemical reaction in a molecular beam, we show the change in the radial distribution function following the formation of CF_3 radical after dissociation of CF_3l. The total experimental temporal resolution is discussed in terms of the electron pulse width and velocity mismatch. The electron pulse was characterized temporally with a streaking technique that yielded the width as a function of the number of electrons per pulse. Experimental results show that the electron source produces picosecond (or less) pulses at densities of 100 electrons per pulse and 10-ps pulses at 1000 electrons per pulse. We also report our observation of a novel photoionization-induced lensing effect on the undiffracted electron beam, which we have used to establish time zero for UED when reactions are initiated by a laser pulse.",
"doi": "10.1021/j100062a011",
"issn": "0022-3654",
"publisher": "American Chemical Society",
"publication": "Journal of Physical Chemistry",
"publication_date": "1994-03-01",
"series_number": "11",
"volume": "98",
"issue": "11",
"pages": "2782-2796"
},
{
"id": "authors:q952k-wcp82",
"collection": "authors",
"collection_id": "q952k-wcp82",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160826-104207140",
"type": "article",
"title": "Femtosecond reaction dynamics of Rydberg states. Methyl iodide",
"author": [
{
"family_name": "Janssen",
"given_name": "M. H. M.",
"clpid": "Janssen-M-H-M"
},
{
"family_name": "Dantus",
"given_name": "M.",
"clpid": "Dantus-M"
},
{
"family_name": "Guo",
"given_name": "H.",
"clpid": "Guo-H"
},
{
"family_name": "Zewail",
"given_name": "A. H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "Femtosecond reaction dynamics of Rydberg states (6p ^2E_(1/2) and 7s^2E_(3/2)) in methyl iodide are reported. The observed ultrafast decay and the large isotope effect reflect the Rydberg-valence potentials crossing to yield CH_3 + I. The dependence of the dynamics on the vibrational mode is studied with focus on the character of the mode and the coherent coupling. Molecular quantum dynamics simulations are also reported.",
"doi": "10.1016/0009-2614(93)85635-2",
"issn": "0009-2614",
"publisher": "Elsevier",
"publication": "Chemical Physics Letters",
"publication_date": "1993-11-05",
"series_number": "3-4",
"volume": "214",
"issue": "3-4",
"pages": "281-289"
},
{
"id": "authors:srj4k-x7350",
"collection": "authors",
"collection_id": "srj4k-x7350",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160829-150315344",
"type": "article",
"title": "Ultrafast diffraction and molecular structure",
"author": [
{
"family_name": "Williamson",
"given_name": "J. C.",
"clpid": "Williamson-J-C"
},
{
"family_name": "Dantus",
"given_name": "M.",
"clpid": "Dantus-M"
},
{
"family_name": "Kim",
"given_name": "S. B.",
"clpid": "Kim-S-B"
},
{
"family_name": "Zewail",
"given_name": "A. H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "We report our first successful ultrafast electron diffraction from beams of isolated molecules, CCI_4, I_2, and CF_3I. To demonstrate the feasibility of studying reactions, we report results on the structure of CF_3 radical from the dissociation of CF_3I.",
"doi": "10.1016/0009-2614(92)85988-M",
"issn": "0009-2614",
"publisher": "Elsevier",
"publication": "Chemical Physics Letters",
"publication_date": "1992-08-28",
"series_number": "6",
"volume": "196",
"issue": "6",
"pages": "529-534"
},
{
"id": "authors:332cm-tfw84",
"collection": "authors",
"collection_id": "332cm-tfw84",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160829-150315920",
"type": "article",
"title": "Femtochemistry: recent advances and extension to high pressures",
"author": [
{
"family_name": "Zewail",
"given_name": "A. H.",
"clpid": "Zewail-A-H"
},
{
"family_name": "Dantus",
"given_name": "M.",
"clpid": "Dantus-M"
},
{
"family_name": "Bowman",
"given_name": "R. M.",
"clpid": "Bowman-R-M"
},
{
"family_name": "Mokhtari",
"given_name": "A.",
"clpid": "Mokhtari-A"
}
],
"abstract": "Recent advances made in laser femtochemistry are presented. Extensions to the high pressure regime (and liquids) are demonstrated, using an example, the classic case of iodine dissociation and recombination. In femtochemistry the motion of the nuclei is followed with femtosecond time resolution and the dynamics are studied during the course of the reaction \u2014 the transition states. The examples given here draw on increasing complexity \u2014 from elementary chemical reactions under isolated molecular conditions to more complex reactions with many degrees of freedom, and move toward the condensed phase limit.",
"doi": "10.1016/1010-6030(92)85061-X",
"issn": "1010-6030",
"publisher": "Elsevier",
"publication": "Journal of Photochemistry and Photobiology A: Chemistry",
"publication_date": "1992-01-15",
"series_number": "3",
"volume": "62",
"issue": "3",
"pages": "301-319"
},
{
"id": "authors:q57r3-2z520",
"collection": "authors",
"collection_id": "q57r3-2z520",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160830-102557283",
"type": "article",
"title": "Femtosecond probing of molecular dynamics by mass-spectrometry in a molecular beam",
"author": [
{
"family_name": "Dantus",
"given_name": "M.",
"clpid": "Dantus-M"
},
{
"family_name": "Janssen",
"given_name": "M. H. M.",
"clpid": "Janssen-M-H-M"
},
{
"family_name": "Zewail",
"given_name": "A. H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "Femtosecond probing of molecular dynamics using mass-spectrometry in a molecular beam is reported. The probing is made using multiphoton ionization of a skimmed molecular beam followed by time-of-flight ion detection. Studies of CH_3I, CD_3I and I_2 have been made, and here we report our observation of wave-packet motion, the vibrational and rotational dynamics, and the femtosecond predissociation dynamics of Rydberg states. The mass-selection makes it now possible to study fragmentation and ionization on the femtosecond time scale.",
"doi": "10.1016/0009-2614(91)80071-5",
"issn": "0009-2614",
"publisher": "Elsevier",
"publication": "Chemical Physics Letters",
"publication_date": "1991-06-28",
"series_number": "4",
"volume": "181",
"issue": "4",
"pages": "281-287"
},
{
"id": "authors:0wj1x-gdh38",
"collection": "authors",
"collection_id": "0wj1x-gdh38",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160830-102642301",
"type": "article",
"title": "Femtosecond multiphoton dynamics of higher-energy potentials",
"author": [
{
"family_name": "Bowman",
"given_name": "R. M.",
"clpid": "Bowman-R-M"
},
{
"family_name": "Dantus",
"given_name": "M.",
"clpid": "Dantus-M"
},
{
"family_name": "Zewail",
"given_name": "A. H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "The real-time motion of wave packets prepared coherently in different potential energy surfaces of molecular iodine is reported. Using multiphoton excitation and depletion techniques, we observe the phase-shifted oscillatory motion of the packet and the different transients characteristic of the bound B 0^+u(^3\u03a0) and D 0^+u(^1\u03a3) state potentials along with the repulsive 0^+g (^1\u03a0) state potential. The approach helps in extending FTS to higher energy potentials and \"dark\" states, and illustrates experimental control schemes in a relatively simple system.",
"doi": "10.1016/0009-2614(90)85484-T",
"issn": "0009-2614",
"publisher": "Elsevier",
"publication": "Chemical Physics Letters",
"publication_date": "1990-11-23",
"series_number": "6",
"volume": "174",
"issue": "6",
"pages": "546-552"
},
{
"id": "authors:vspje-9pb34",
"collection": "authors",
"collection_id": "vspje-9pb34",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160830-102643027",
"type": "article",
"title": "Femtosecond selective control of wave packet population",
"author": [
{
"family_name": "Gerdy",
"given_name": "J. J.",
"clpid": "Gerdy-J-J"
},
{
"family_name": "Dantus",
"given_name": "M.",
"clpid": "Dantus-M"
},
{
"family_name": "Bowman",
"given_name": "R. M.",
"clpid": "Bowman-R-M"
},
{
"family_name": "Zewail",
"given_name": "A. H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "Femtosecond selective control of wave packet population is reported for molecular iodine. It is shown that both population and phase control of the packet motion can be observed by a 2-D pulse sequence of variable delay times and phase angles. Extension to other type of control experiments is also discussed.",
"doi": "10.1016/0009-2614(90)80039-G",
"issn": "0009-2614",
"publisher": "Elsevier",
"publication": "Chemical Physics Letters",
"publication_date": "1990-07-27",
"series_number": "1-2",
"volume": "171",
"issue": "1-2",
"pages": "1-4"
},
{
"id": "authors:60txk-tzp07",
"collection": "authors",
"collection_id": "60txk-tzp07",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160831-091534221",
"type": "article",
"title": "Femtosecond temporal spectroscopy and direct inversion to the potential: Application to iodine",
"author": [
{
"family_name": "Gruebele",
"given_name": "M.",
"clpid": "Gruebele-M"
},
{
"family_name": "Roberts",
"given_name": "G.",
"clpid": "Roberts-G"
},
{
"family_name": "Dantus",
"given_name": "M.",
"clpid": "Dantus-M"
},
{
"family_name": "Bowman",
"given_name": "R. M.",
"clpid": "Bowman-R-M"
},
{
"family_name": "Zewail",
"given_name": "A. H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "The use of femtosecond lasers in probing molecular dynamics is usually thought to yield improved temporal resolution, at the expense of spectral information. Here, we report on the use of femtosecond temporal spectroscopy (FTS) to yield accurate spectral information (vibrational and rotational) and to invert directly to the potential energy curve. As an example, we present the FTS analysis, inversion to the potential, and confirmatory wave packet calculations for the B ^3\u03a0_(0+u) state of molecular iodine.",
"doi": "10.1016/0009-2614(90)87134-D",
"issn": "0009-2614",
"publisher": "Elsevier",
"publication": "Chemical Physics Letters",
"publication_date": "1990-03-09",
"series_number": "5-6",
"volume": "166",
"issue": "5-6",
"pages": "459-469"
},
{
"id": "authors:efr2z-nbc49",
"collection": "authors",
"collection_id": "efr2z-nbc49",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150407-154455895",
"type": "article",
"title": "Femtosecond laser observations of molecular vibration and rotation",
"author": [
{
"family_name": "Dantus",
"given_name": "M.",
"clpid": "Dantus-M"
},
{
"family_name": "Bowman",
"given_name": "R. M.",
"clpid": "Bowman-R-M"
},
{
"family_name": "Zewail",
"given_name": "A. H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "Ultrafast molecular vibrations and rotations are the fundamental motions that characterize chemical bonding and determine reaction dynamics at the molecular level. The timescales for these motions are typically 10^(\u221210) s for vibrations and 10^(\u221213) s for rotations. For decades, time-integrated (frequency-resolved) spectros-copy has provided a powerful tool for probing the dynamics of motion, but the motions themselves are not 'seen' directly in real-time. With femtosecond laser techniques it is now possible to follow the motions of isolated molecular systems as they occur. The requirement is that the system is excited (for vibration) and aligned (for rotation) on a timescale shorter than the vibrational and rotational periods. Here we report real-time observations of these molecular motions. The system\u2014in this case, molecular iodine\u2014is prepared in the particular state(s) of interest by coherent excitation with an initial femtosecond laser pulse, and the subsequent motions are probed with successive femtosecond pulses. The probe monitors changes in the interatomic distance (vibration) or molecular orientation (rotation), so that the measured signal provides direct 'snapshots' of the molecular motions.",
"doi": "10.1038/343737a0",
"issn": "0028-0836",
"publisher": "Nature Publishing Group",
"publication": "Nature",
"publication_date": "1990-02-22",
"series_number": "6260",
"volume": "343",
"issue": "6260",
"pages": "737-739"
},
{
"id": "authors:kjcrf-tt542",
"collection": "authors",
"collection_id": "kjcrf-tt542",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DANjcp89",
"type": "article",
"title": "Femtosecond real-time probing of reactions. V. The reaction of IHgI",
"author": [
{
"family_name": "Dantus",
"given_name": "M.",
"clpid": "Dantus-M"
},
{
"family_name": "Bowman",
"given_name": "R. M.",
"clpid": "Bowman-R-M"
},
{
"family_name": "Gruebele",
"given_name": "M.",
"clpid": "Gruebele-M"
},
{
"family_name": "Zewail",
"given_name": "A. H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "The dissociation reaction of HgI2 is examined experimentally using femtosecond transition-state spectroscopy (FTS). The reaction involves symmetric and antisymmetric coordinates and the transition-state is well-defined: IHgI*-->[IHgI][double-dagger]@B|Q[sub S[script ']]Q[sub a[script ']]q-->HgI+I. FTS is developed for this class of ABA-type reactions and recurrences are observed for the vibrating fragments (symmetric coordinate) along the reaction coordinate (antisymmetric coordinate). The translational motion is also observed as a \"delay time\" of the free fragments. Analysis of our FTS results indicates that the reaction wave packet proceeds through two pathways, yielding either I(2P3/2) or I*(2P1/2) as one of the final products. Dissociation into these two pathways leads to HgI fragments with different vibrational energy, resulting in distinct trajectories. Hence, oscillatory behaviors of different periods in the FTS transients are observed depending on the channel probed (~300 fs to ~1 ps). These results are analyzed using the standard FTS description, and by classical trajectory calculations performed on model potentials which include the two degrees of freedom of the reaction. Quantum calculations of the expected fluorescence of the fragment are also performed and are in excellent agreement with experiments.",
"doi": "10.1063/1.457267",
"issn": "0021-9606",
"publisher": "American Institute of Physics",
"publication": "Journal of Chemical Physics",
"publication_date": "1989-12-15",
"series_number": "12",
"volume": "91",
"issue": "12",
"pages": "7437-7450"
},
{
"id": "authors:z1teq-cm535",
"collection": "authors",
"collection_id": "z1teq-cm535",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160902-105849708",
"type": "article",
"title": "Femtosecond transition-state spectroscopy of iodine: From strongly bound to repulsive surface dynamics",
"author": [
{
"family_name": "Bowman",
"given_name": "R. M.",
"clpid": "Bowman-R-M"
},
{
"family_name": "Dantus",
"given_name": "M.",
"clpid": "Dantus-M"
},
{
"family_name": "Zewail",
"given_name": "A. H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "The application of femtosecond transition-state spectroscopy (FTS) to molecular iodine is reported. The real-time motion of wave packets prepared coherently in the bound B state is observed. In addition, the motion is probed near and above the dissociation limit for the reaction: I_2\u2192I(^2P_(3/2))+I^*(^2P^(1/2)). FTS measurements of the dynamics on repulsive surfaces are also reported.",
"doi": "10.1016/0009-2614(89)85088-2",
"issn": "0009-2614",
"publisher": "Elsevier",
"publication": "Chemical Physics Letters",
"publication_date": "1989-09-22",
"series_number": "4-5",
"volume": "161",
"issue": "4-5",
"pages": "297-302"
},
{
"id": "authors:zn3zc-asa47",
"collection": "authors",
"collection_id": "zn3zc-asa47",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160902-105851252",
"type": "article",
"title": "Femtochemistry of the reaction: IHgI^*\u2192[IHg\u2026I]^(\u2021*)\u2192HgI+I",
"author": [
{
"family_name": "Bowman",
"given_name": "R. M.",
"clpid": "Bowman-R-M"
},
{
"family_name": "Dantus",
"given_name": "M.",
"clpid": "Dantus-M"
},
{
"family_name": "Zewail",
"given_name": "A. H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "Femtochemistry of the reaction IHgI^*\u2192[IHg\u2026I]^(\u2021*)\u2192HgI+I is reported. We observe femtosecond decays with an oscillatory modulation. These observations are related to the reaction trajectories on the global PES, which involve a symmetric stretch, an antisymmetric stretch and a bend.",
"doi": "10.1016/S0009-2614(89)87108-8",
"issn": "0009-2614",
"publisher": "Elsevier",
"publication": "Chemical Physics Letters",
"publication_date": "1989-03-31",
"series_number": "2-3",
"volume": "156",
"issue": "2-3",
"pages": "131-137"
},
{
"id": "authors:8x0qr-yfg76",
"collection": "authors",
"collection_id": "8x0qr-yfg76",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160902-131819394",
"type": "article",
"title": "Femtosecond real-time probing of reactions. II. The dissociation reaction of ICN",
"author": [
{
"family_name": "Dantus",
"given_name": "Marcos",
"clpid": "Dantus-M"
},
{
"family_name": "Rosker",
"given_name": "Mark J.",
"clpid": "Rosker-M-J"
},
{
"family_name": "Zewail",
"given_name": "Ahmed H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "Experimental results obtained for the dissociation reaction ICN^*\u2192[I\u22c5\u22c5\u22c5CN]^(\u2021*)\u2192I+CN using femtosecond transition\u2010state spectroscopy (FTS) are presented. The process of the I\u2013CN bond breaking is clocked, and the transition states of the reaction are observed in real time. From the clocking experiments, a \"dissociation\" time of 205\u00b130 fs was measured and was related to the length scale of the potential. The transition states live for only \u223c50 fs or less, and from the observed transients we deduce some characteristics of the relevant potential energy surfaces (PES). These FTS experiments are discussed in relation to both classical and quantum mechanical models of the dynamical motion, including features of the femtosecondcoherence and alignment of fragments during recoil. The observations are related to the radial and angular properties of the PES.",
"doi": "10.1063/1.455428",
"issn": "0021-9606",
"publisher": "American Institute of Physics",
"publication": "Journal of Chemical Physics",
"publication_date": "1988-11-15",
"series_number": "10",
"volume": "89",
"issue": "10",
"pages": "6128-6140"
},
{
"id": "authors:yrx9a-8hz26",
"collection": "authors",
"collection_id": "yrx9a-8hz26",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160902-131819082",
"type": "article",
"title": "Femtosecond real-time probing of reactions. I. The technique",
"author": [
{
"family_name": "Rosker",
"given_name": "Mark J.",
"clpid": "Rosker-M-J"
},
{
"family_name": "Dantus",
"given_name": "Marcos",
"clpid": "Dantus-M"
},
{
"family_name": "Zewail",
"given_name": "Ahmed H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "When a chemical bond is broken in a direct dissociationreaction, the process is so rapid that it has generally been considered instantaneous and therefore unobservable. But the fragments formed interact with one another for times on the order of 10^(\u221213) s after the photon has been absorbed. On this time scale the system passes through intermediate transition configurations; the totality of such configurations have been, in the recent literature, designated as \"transition states.\" Femtosecond transition\u2010state spectroscopy (FTS) is a real\u2010time technique for probing chemical reactions. It allows the direct observation of a molecule in the process of falling apart or in the process of formation. In this paper, the first in a series on femtosecond real\u2010time probing of reactions, we examine the technique in detail. The concept of FTS is explored, and the interrelationship between the dynamics of chemical reactions and molecular potential energy surfaces is considered. The experimental method, which requires the generation of spectrally tunable femtosecond optical pulses, is detailed. Illustrative results from FTS experiments for several elementary reactions are presented, and we describe methods for relating these results to the potential energy surface(s).",
"doi": "10.1063/1.455427",
"issn": "0021-9606",
"publisher": "American Institute of Physics",
"publication": "Journal of Chemical Physics",
"publication_date": "1988-11-15",
"series_number": "10",
"volume": "89",
"issue": "10",
"pages": "6113-6127"
},
{
"id": "authors:bw8p0-gd291",
"collection": "authors",
"collection_id": "bw8p0-gd291",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141222-152314297",
"type": "article",
"title": "Femtosecond Clocking of the Chemical Bond",
"author": [
{
"family_name": "Rosker",
"given_name": "Mark J.",
"clpid": "Rosker-M-J"
},
{
"family_name": "Dantus",
"given_name": "Marcos",
"clpid": "Dantus-M"
},
{
"family_name": "Zewail",
"given_name": "Ahmed H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "When a chemical bond is broken in a direct dissociation reaction, the process is so rapid that it has generally been considered instantaneous and thus unmeasurable. However, the bond does persist for times on the order of 10^(-13) seconds after the photon has been absorbed. Femtosecond (10^(-15) second) laser techniques can be used to directly clock this process, which describes the dynamics of the chemical bond. The time required to break the chemical bond in an elementary reaction has been measured and the characteristic repulsion length for the potential governing fragment separation has been obtained.",
"doi": "10.1126/science.241.4870.1200",
"issn": "0036-8075",
"publisher": "American Association for the Advancement of Science",
"publication": "Science",
"publication_date": "1988-09-02",
"series_number": "4870",
"volume": "241",
"issue": "4870",
"pages": "1200-1202"
},
{
"id": "authors:xp2kh-kkw08",
"collection": "authors",
"collection_id": "xp2kh-kkw08",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160906-090611348",
"type": "article",
"title": "Stepwise Solvation of the Intramolecular-Charge-Transfer Molecule p-(Dimethylamino)benzonitrile",
"author": [
{
"family_name": "Peng",
"given_name": "Lawrence W.",
"clpid": "Peng-Lawrence-W"
},
{
"family_name": "Dantus",
"given_name": "Marcos",
"clpid": "Dantus-M"
},
{
"family_name": "Zewail",
"given_name": "Ahmed H.",
"clpid": "Zewail-A-H"
},
{
"family_name": "Kemnitz",
"given_name": "Klaus",
"clpid": "Kemnitz-K"
},
{
"family_name": "Hicks",
"given_name": "Janice M.",
"clpid": "Hicks-J-M"
},
{
"family_name": "Eisenthal",
"given_name": "Kenneth B.",
"clpid": "Eisenthal-K-B"
}
],
"abstract": "This paper presents a systematic study of gas-phase p-(N,N-dimethy1amino)benzonitrile (DMABN) both in a supersonic\njet expansion and in a thermalized vapor. From the jet studies, the excited- and ground-state vibrational spectra of the isolated molecule are resolved, and the spectroscopy of the stoichiometric complex with water, methanol, ammonia, and acetonitrile in the beam is reported. It is concluded that 1:l complexes are not sufficient for the local perturbation to cause charge separation. At higher temperatures in the jet, we observe emission that we attribute to DMABN self-complexes. Under high pressure\nand temperature vapor conditions (>30 mTorr, 60 \u00b0C), red-shifted fluorescence from DMABN is observed. This is attributed to the charge-transfer state of DMABN in self-complexes.",
"doi": "10.1021/j100308a021",
"issn": "0022-3654",
"publisher": "American Chemical Society",
"publication": "Journal of Physical Chemistry",
"publication_date": "1987-11-19",
"series_number": "24",
"volume": "91",
"issue": "24",
"pages": "6162-6167"
},
{
"id": "authors:ncx6k-3e126",
"collection": "authors",
"collection_id": "ncx6k-3e126",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160906-090611693",
"type": "article",
"title": "Real-time femtosecond probing of \"transition states\" in chemical reactions",
"author": [
{
"family_name": "Dantus",
"given_name": "Marcos",
"clpid": "Dantus-M"
},
{
"family_name": "Rosker",
"given_name": "Mark J.",
"clpid": "Rosker-M-J"
},
{
"family_name": "Zewail",
"given_name": "Ahmed H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "[No abstract]",
"doi": "10.1063/1.453122",
"issn": "0021-9606",
"publisher": "American Institute of Physics",
"publication": "Journal of Chemical Physics",
"publication_date": "1987-08-15",
"series_number": "4",
"volume": "87",
"issue": "4",
"pages": "2395-2397"
},
{
"id": "authors:415aj-rzt25",
"collection": "authors",
"collection_id": "415aj-rzt25",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160920-093337135",
"type": "article",
"title": "Real-time measurements of IVR versus inferences from spectral broadening data: the alkylanilines \"ring + tail\" system",
"author": [
{
"family_name": "Baskin",
"given_name": "J. S.",
"clpid": "Baskin-J-S"
},
{
"family_name": "Dantus",
"given_name": "M.",
"clpid": "Dantus-M"
},
{
"family_name": "Zewail",
"given_name": "A. H.",
"clpid": "Zewail-A-H"
}
],
"abstract": "We report on picosecond/molecular beam studies of alkylanilines. The studies reveal important discrepancies between real-time measurements and inferences from spectral broadening data. We observe quantum recurrences and we find that the observed severe spectral congestion does not correspond to the observed coherence. The effect of mode symmetry and energy on IVR dynamics is also examined.",
"doi": "10.1016/0009-2614(86)80242-1",
"issn": "0009-2614",
"publisher": "Elsevier",
"publication": "Chemical Physics Letters",
"publication_date": "1986-10-24",
"series_number": "6",
"volume": "130",
"issue": "6",
"pages": "473-481"
}
]