Εξειδίκευση τύπου :	Άρθρο σε επιστημονικό περιοδικό
Τίτλος:	Ultrafast time delay as a control parameter in resonant ionization by two XUV ultrashort pulses
Δημιουργός/Συγγραφέας:	[EL] Μερκούρης, Θεόδωρος Δ.[EN] Mercouris, Theodoros D. [EL] Κομνηνός, Γιάννης[EN] Komninos, Yannis [EL] Νικολαΐδης, Κλεάνθης A.[EN] Nicolaides, Cleanthes A.
Εκδότης:	IOP Publishing
Ημερομηνία:	2020
Γλώσσα:	Αγγλικά
ISSN:	0953-4075 1361-6455
DOI:	10.1088/1361-6455/ab787b
Περίληψη:	We predict quantitatively that it is possible to use few-femtosecond positive or negative time delays, ${\rm{\Delta }}t,$ between two XUV Gaussian few-femtosecond pulses of moderate intensities and central frequencies ${\omega }_{1}$ and ${\omega }_{2},$ in order to control the probability of ionization at clearly defined exit energies corresponding to the sums of photon frequencies (${\omega }_{1}+{\omega }_{1}$), (${\omega }_{2}+{\omega }_{2}$), and (${\omega }_{1}+{\omega }_{2},$ or ${\omega }_{2}+{\omega }_{1}$). The phenomenon is demonstrated quantitatively by obtaining and using nonperturbative solutions of the time-dependent Schrödinger equation for a time-dependent scheme involving the process of two-photon resonant ionization of Helium via the $1s2p$ ${}^{1}P^{o}$ (58.4 nm) and $1s4p$ ${}^{1}P^{o}$ (52.22 nm) excited states. The calculations used wavefunctions which are state-specific for the discrete spectrum, (up to the $1s7g$ ${}^{1}G$ Rydberg state), as well as for the energy-normalized continuous spectrum, (up to 2.0 a.u. above threshold with angular momenta ${\ell }$ = 0, 1, 2, 3, 4). For this system, using ${\rm{\Delta }}t$ as a control knob, the effects on the photoelectron spectrum of the combination of the transition amplitudes via the two paths and their interference are determined clearly for pulses with field-cycles ranging from about 15 to about 80 cycles. The analysis has included the comparison of the nonperturbative results, obtained by implementing the state-specific expansion approach, with those obtained from the application of second order time-dependent perturbation theory with two Gaussian pulses of finite duration.
Τίτλος πηγής δημοσίευσης:	Journal of Physics B: Atomic, Molecular and Optical Physics
Τόμος/Κεφάλαιο:	53
Τεύχος:	9
Σελίδες:	095603
Θεματική Κατηγορία:	[EL] Φυσική και θεωρητική χημεία[EN] Physical and theoretical chemistry [EL] Φασματοσκοπία[EN] Spectroscopy [EL] Ατομική φυσική (συμπ. μοριακή φυσική, σχετικότητα, κβαντική θεωρία και φυσική στερεάς κατάστασης)[EN] Atomic physics (Incl. molecular physics, relativity, quantum theory, and solid state physics)
Λέξεις-Κλειδιά:	Atomic processes in external fields Ultrafast time delay control Multiphoton ionization
Κάτοχος πνευματικών δικαιωμάτων:	Copyright © 2020 IOP Publishing Ltd
Ηλεκτρονική διεύθυνση στον εκδότη (link):	https://iopscience.iop.org/article/10.1088/1361-6455/ab787b
Ηλεκτρονική διεύθυνση περιοδικού (link) :	https://iopscience.iop.org/journal/0953-4075
Εμφανίζεται στις συλλογές:	Ινστιτούτο Θεωρητικής και Φυσικής Χημείας (ΙΘΦΧ) - Επιστημονικό έργο