Efficient x-ray line production from laser excited CF₂Cl₂clusters. Mixed cluster formation and control of the x-ray line yield

Abstract

We report on effective x-ray generation under excitation of clusters of polyatomic CF 2 Cl 2 molecules by femtosecond laser radiation of moderate intensity I ≈ 5 × 10 15 W cm −2 (E ≈ 5 mJ). The maximal laser energy conversion efficiency to chlorine x-ray lines (E = 2.6-2.8 keV) reached 2 × 10 −5 when the CF 2 Cl 2 clusters were formed in the presence of the carrier gas helium. It was demonstrated that the spectrum of laser-induced x-rays can be used to detect mixed clusters, appearing in a 3% mixture of CF 2 Cl 2 with Ar. We proposed adding a light thermalizing gas to the mixture, i.e., using a ternary mixture CF 2 Cl 2 -Ar-He, to control the fraction of components that the mixed clusters are composed of. We have given the first demonstration of a dual-energy x-ray source with a tunable line amplitude that is controlled by the helium fraction in the mixture.

Interaction of High-Intensity Femtosecond Radiation With Gas Cluster Beam: Effect of Pulse Duration on Joint Terahertz and X-Ray Emission

“…The efficiency raised up to 7 · 10 −6 in the case when transform-limited laser pulse (τ ≈ 50 fs, E ≈ 25 mJ) was applied. The measured estimated X-ray generation efficiency was the same order with an efficiency obtained in our previous experiments that were carried out with argon clusters excited by the laser pulse with the energy of about 5 mJ focused at a distance of 2 mm from the nozzle outlet [16], [17]. We suppose that in the present experiment, the same efficiency was obtained due to the larger distance between the interaction zone and the nozzle outlet, i.e., smaller cluster size was compensated by the larger laser pulse energy.…”

“…One of the most exciting effects that was observed in cluster matter was the emission of powerful X-ray pulse [3], [4], [16], [17]. Later this effect was phenomenologically explained in [18] and [19] using the following arguments.…”

Femtosecond laser excitation of mixed Ar/Kr clusters: peculiarities of K-line x-ray production from nanoplasma under varied fraction of initial gas components

“…corresponding line in x-ray spectrum. Previously, we demonstrated that mixed CF 2 Cl 2 -Ar clusters can be detected by the chlorine and argon lines in x-ray spectrum [11].…”

“…Femtosecond laser excitation of mixed Ar/Kr clusters: peculiarities of K-line x-ray production from nanoplasma under varied fraction of initial gas components I A Zhvaniya, M S Dzhidzhoev and V M Gordienko on the enhancement of laser energy absorption and due to this reason the production of high-energy ions, electrons and x-ray photons significantly increases [10]. We have previously shown that it is possible to utilize mixed clusters as a target to obtain a dual-energy ultrashort x-ray radiation induced by femtosecond laser [11], concurrently to the alternative multienergy x-ray sources, based on Compton and Thomson scattering [12] and synchrotrons [13].…”

Stability of normal modes of a polyatomic molecule under laser-induced modification of its geometry

“…A number of effects of interaction of laser radiation with polyatomic molecules have been recently studied, both experimantally and theoretically. For instance, one can mention laser-driven synthesis of chemical products [1,2], laser control of molecular electron motion [3,4], control of optical properties of a gas of coherently spinning molecules [5][6][7][8], laser-induced pyrolysis of a monosilane and boron trichloride [9], x-ray generation under interaction of femtosecond laser pulses with clusters of polyatomic molecules [10], SF − 6 anion observation [11,12] and F − (NF 3 ) n double detachment [13].…”