Proton induced monochromatic X-ray beams: A versatile source for resonant Raman scattering studies A.G. Karydas a, * , M. Budnar b ,  Z.  Smit b,c , Ch. Zarkadas a , T. Paradellis a a Laboratory for Material Analysis, Institute of Nuclear Physics, NCSR ‘‘Demokritos’’, Aghia Paraskevi, 153 10 Athens, Greece b Institute Jo zef Stefan, Jamova 39, 1000 Ljubljana, Slovenia c Department of Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia Abstract Resonant raman scattering (RRS) can contribute considerably, under specific experimental conditions, to the at- tenuation of X-rays in matter. The experimental study of the RRS can lead to a better assessment of this contribution. In this work low energy proton induced vanadium Ka X-rays have been utilized in two different X-ray production geometries for RRS studies. The KL-RRS cross-sections for titanium and vanadium and the LM-RRS for cesium and barium are measured respectively, while the importance of the technique in the systematic measurement of X-ray in- teraction cross-sections in matter is also discussed. Ó 2002 Elsevier Science B.V. All rights reserved. PACS: 78.70.Ck; 41.50; 32.80.Cy; 32.90.þa Keywords: Inelastic X-ray scattering; Resonant Raman scattering; PIXE; Monochromatic X-ray beams; Cross-sections 1. Introduction Resonant Raman scattering (RRS) is an in- elastic process, which exhibits fundamental differ- ences compared to other scattering interactions between X-rays and atoms (Rayleigh and Comp- ton scattering) [1,2]. Its main characteristic is the occurrence of a strong resonant behavior, as the energy of the incident radiation approaches from lower energies an absorption edge of the target element. The evolution of the RRS process can be explained and described quantitatively via the second order perturbation theory, through the interaction term ~ p  A * . For example, when the in- cident radiation has energy E 0 , such that E 0 6 U K (U K is the binding energy of the K-shell), the KL type of RRS proceeds through an intermediate state, where a virtual hole is created in the K-shell and the corresponding electron is transferred to an unoccupied state either in the continuum or in a bound excited state. In the final state, a scattered photonisemitted,whereasanelectronfromoneof the L subshells fills the hole. Since the energy dif- ference E 0  U L is shared between the scattered photon with energy E s and the emitted electron, the onset of the RRS distribution is expected to appear at the maximum scattered photon energy E max s ¼ E 0  U L , which corresponds to a kinetic energy of the emitted electron equal to zero. The RRS contribution to the attenuation of X- rays in matter has not been included yet in the Nuclear Instruments and Methods in Physics Research B 189 (2002) 43–48 www.elsevier.com/locate/nimb * Corresponding author. Tel.: +30-1-651-8770; fax: +30-1- 651-1215. E-mail address: karydas@mail.demokritos.gr(A.G.Karydas). 0168-583X/02/$ - see front matter Ó 2002 Elsevier Science B.V. All rights reserved. PII:S0168-583X(01)00992-2