Coherent Control of Photofragment Separation in the Dissociative Ionization of IBr

Ohmura, Hideki; Nakanaga, Taisuke; Tachiya, M.

doi:10.1103/physrevlett.92.113002

Cited by 73 publications

(41 citation statements)

References 35 publications

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“…For IBr molecules, geometric orientation dominated for subpicosecond pulses because they are heavy, such as I 2 and Br 2 . 11,12 For iodinecontaining molecules, the orientation effect ͑modulation depth͒ improves in spite of the increase of the moment of inertia from CH 3 I to C 3 H 5 I, shown in Fig. 4.…”

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confidence: 93%

“…In our preceding paper we demonstrated the orientation sensitive ionization based on quantum interference in the dissociative ionization of IBr. 11 So far, to our knowledge, molecular orientation using the ϩ2 scheme has not been experimentally tested.…”

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confidence: 99%

“…We can determine the kinetic energy of the photofragments using one-photon dissociation by nanosecond lasers. 11 Kinetic energy scales are shown in the expanded view of Fig. 3.…”

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confidence: 99%

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Quantum control of molecular orientation by two-color laser fields

Ohmura

Nakanaga

2004

The Journal of Chemical Physics

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We demonstrate molecular orientation by using phase-controlled two-color omega+2omega laser pulses with an intensity of 1.0x10(12) W/cm(2) and a pulse duration of 130 fs. The orientation of three iodine-containing molecules (IBr, CH(3)I, and C(3)H(5)I) was monitored by the directional asymmetries of the photofragment angular distribution in dissociative ionization. In all three molecules, the directional asymmetry showed an oscillating behavior dependent on the relative phase difference between omega and 2omega pulses. The phase dependence of the directional asymmetry observed in iodine ions and counterpart ions were out of phase with each other. This result shows that a phase-controlled omega+2omega optical field discriminates between parallel and antiparallel configurations of aligned molecules that have a permanent dipole. This method performed well because (1) molecular orientation can be achieved by all-optical fields; (2) the direction of orientation is easily switched by changing the sign of the quantum interference; and (3) this method is free from any resonance constraint and thus can be applied to any molecule.

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Quantum control of molecular orientation by two-color laser fields

Ohmura

Nakanaga

2004

The Journal of Chemical Physics

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“…For example, the path alternatives are given by the two excitation processes in a 1 vs. N coherent control scenario. The resultant CCI framework is general and applicable to many systems, from atoms [15,66] to molecules [27,45,[67][68][69] to bulk solids [4,5,20,30,[70][71][72][73][74][75]. Further, the control field can be in a semiclassical coherent or in a quantum state of light, such as a multimode Fock state or a squeezed state.…”

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confidence: 99%

An Approach To “Quantumness” In Coherent Control

Scholak

Brumer

2017

Advances in Chemical Physics

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Developments in the foundations of quantum mechanics have identified several attributes and tests associated with the "quantumness" of systems, including entanglement, nonlocality, quantum erasure, Bell test, etc.. Here we introduce and utilize these tools to examine the role of quantum coherence and nonclassical effects in 1 vs. N photon coherent phase control, a paradigm for an all-optical method for manipulating molecular dynamics. In addition, truly quantum control scenarios are introduced and examined. The approach adopted here serves as a template for studies of the role of quantum mechanics in other coherent control and optimal control scenarios.

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“…By virtue of the synthesized laser field, the energy and angular distributions of emitted electrons can be manipulated. Two-color pulses have been used in investigations of above-threshold ionization of atoms [1][2][3], controlled dissociative ionization [4][5][6], dichroism in ionization [7,8], and orientation of molecules [9]. Recently, they have also been applied to control interference fringes in the momentum distribution of electron emission [10][11][12].…”

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An Ultrafast Switch for Electron Emission

Kealhofer

2016

Physics

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We demonstrate coherent control of multiphoton and above-threshold photoemission from a single solidstate nanoemitter driven by a fundamental and a weak second harmonic laser pulse. Depending on the relative phase of the two pulses, electron emission is modulated with a contrast of the oscillating current signal of up to 94%. Electron spectra reveal that all observed photon orders are affected simultaneously and similarly. We confirm that photoemission takes place within 10 fs. Accompanying simulations indicate that the current modulation with its large contrast results from two interfering quantum pathways leading to electron emission. DOI: 10.1103/PhysRevLett.117.217601 Ionization by two-color laser fields with well-defined relative phase allows one to tune and control electronic dynamics on the (sub)femtosecond time scale. By virtue of the synthesized laser field, the energy and angular distributions of emitted electrons can be manipulated. Two-color pulses have been used in investigations of above-threshold ionization of atoms [1][2][3], controlled dissociative ionization [4][5][6], dichroism in ionization [7,8], and orientation of molecules [9]. Recently, they have also been applied to control interference fringes in the momentum distribution of electron emission [10][11][12]. In this Letter we demonstrate exquisite coherent emission control by simultaneous interaction of fundamental (ω) and second harmonic (2ω) femtosecond laser pulses with condensed matter. Specifically, we control photoemission from an individual nanotip.While nanotips are nowadays routinely used as electron sources in high-resolution electron microscopes [13], their superb transverse coherence known from dc field emission has only recently been observed in photoemission [14]. Field enhancement at the apex of nanotips [15] confines and enhances electron emission, thus enabling the study of strong-field physics with moderate laser intensities well below the damage threshold [16][17][18][19][20][21]. Laser-induced photoemission from tips (for extensive reviews, see Ref.[22]) has already been employed in pulsed electron guns for electron diffraction experiments [23,24], while arrays of nanotips have been fabricated and explored as electron sources for compact coherent x-ray production [25][26][27]. Recently, a ω − 2ω experiment was performed on a silicon tip array, but no phase-resolved signal indicative of coherent control was reported [27].In our experiment, atomic-scale in situ control over the sample surface results in a well-defined nanoemitter that surpasses the limitations of focal averaging and inhomogeneous broadening. We show that electron emission induced by a strong fundamental pulse can be enhanced or suppressed with a contrast of up to 94% when superimposing a weak second harmonic pulse. This scheme thereby allows efficient coherent control of the nanotip photocurrent utilizing the metal-vacuum interface to suppress emission in one direction. Accompanying simulations suggest that the strong modulation can be explained in te...

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Coherent Control of Photofragment Separation in the Dissociative Ionization of IBr

Cited by 73 publications

References 35 publications

Quantum control of molecular orientation by two-color laser fields

Quantum control of molecular orientation by two-color laser fields

An Approach To “Quantumness” In Coherent Control

An Ultrafast Switch for Electron Emission

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