{"title":"A new approach to solving the time-dependent Schrodinger for an atom in a radiation field","authors":"M. Pont, D. Proulx, R. Shakeshaft","doi":"10.1364/swcr.1991.tua5","DOIUrl":"https://doi.org/10.1364/swcr.1991.tua5","url":null,"abstract":"The time-dependent Schrodinger for an atom in a radiation field has a very special form, at least within the dipole approximation: The time-dependence of the Hamiltonian is contained entirely in a c-number which appears as a factor in the interaction, V(t), of the atom with the radiation field. In the velocity gauge this factor is the vector potential, A(t), of the field — we have V(t)= − (e/µc)A (t) • p, where e, µ, and p are the charge, reduced mass, and canonical momentum (in the center of mass frame) of the electron — while in the length gauge this factor is the electric field vector F(t) — we have V(t) = –eF(t) • x, where x is the position coordinate. To our knowledge, this factorization property has not been fully exploited in previous approaches to solving the timedependent Schrodinger equation1. As we show here, in an application to multiphoton ionization of atomic hydrogen, it is an extremely useful property; and although at first sight it would seem to be a unique feature of the atom-radiation system, this is not so, for, as Solov’ev2 has pointed out, the time-dependent Schrödinger equation for colliding atoms or ions can be transformed into a form in which a scaled time-dependence also appears only in c-number factors of the (transformed) interactions.","PeriodicalId":286766,"journal":{"name":"Short-Wavelength Coherent Radiation: Generation and Application","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114157606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Competition between Above-Threshold Ionization and High-Order Harmonic Generation","authors":"M. D. Perry, S. Allendorf, J. Crane","doi":"10.1364/swcr.1991.tua11","DOIUrl":"https://doi.org/10.1364/swcr.1991.tua11","url":null,"abstract":"Both above threshold ionization and high-order harmonic generation are the result of atomic excitation in a manner which cannot be described by lowest-order perturbation theory. By high-order harmonic generation, more correctly, strong-field harmonic generation, we are referring to the generation of harmonic radiation (typically greater than the 7th harmonic) which is not a monotonically decreasing function of harmonic order. This was recently observed by MacPherson, et al1 and later by Ferray, et al.2 On the other hand, above-threshold ionization, the process by which an atom absorbs more photons than the minimum required to ionize, is now a well established phenomena in the interaction of intense radiation (>1013W/cm2) with atoms.3","PeriodicalId":286766,"journal":{"name":"Short-Wavelength Coherent Radiation: Generation and Application","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114834388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Saturation and Kinetic Issues for Optical-Field-Ionized X-Ray Lasers","authors":"D. Eder, P. Amendt, M. Rosen, J. Nash, S. Wilks","doi":"10.1364/swcr.1991.wa6","DOIUrl":"https://doi.org/10.1364/swcr.1991.wa6","url":null,"abstract":"Ultrashort (tp ≤ 100 fs) high intensity (I ≥ 1017 W/cm2) lasers are potential drivers for x-ray lasers with wavelengths below 100 Å. The short wavelengths are obtained by lasing down to the ground state of the ion. We address a number of saturation and kinetic issues that arise from this type of laser. One scheme, that we have consider in detail, is lasing in the 3d - 2p transitions in Li-like Ne at 98 Å. We have found that for a UV driver (λ = 0.25 µm) stimulated Raman heating is reduced sufficiently to obtain high gains and reasonable efficiencies. Raman heating is a potential barrier for extending the scheme to shorter wavelengths due to the required higher intensities and corresponding increase in heating.","PeriodicalId":286766,"journal":{"name":"Short-Wavelength Coherent Radiation: Generation and Application","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125608709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}