Esposito, A

Mobilio, S

Parthasaradhi, K

Pelliccioni, M

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N O T EIndian J. Phys. 6 9 A  (2), 291 -  293 (1995)L_i j  p  ■an lhtemulumal |<mii nalPhoton attenuation coefficients near L3 edge of Pt in Pt-Rh alloyK Parlhasaradhi, A Kspositn', S Mohilio* and M Pcllicciom ncpartmcnl of Nuclcai lJhysics, Andhra UniVL'isily Visakliapainam MO (MH, IndiaR e t e i v c t j  1 5  f u l \  I W W  i u t c f ) ! n l  1 7  S c f i i n n b a  /d ‘V*/Abstract : Photon alicnualion spcvtij ai L , edge ol Pi and ol Pi in Pt-Rh (XOrf , 20V? ) alloy aie recorded using synchrolion 1 ail 1 .it 1 on An anaUsis ol the speUia icvcaled that tin- clleei ol alloying on the photon attenuation Loclficicnl in Pi aiound 1M edge is ol the oidei ol 12VrKeywords : Pholon aileiuialion coeMieienl, Pt RJi alloy, .synchrotron ladialioii PACS Nos. : 32 80 1A lew allcmpls were made by Joga Ran etui [1|. Nageswara Rao etui |2| and Seetharami Reddy cl al [3] to look for the possible alloying effects on photon attenuation coefficients in the region of absorption edges However, not much evidence was noticed All these measurements were carried out on a good geometry set-up employing X-rays 0 1  low eneigy gamma rays with high resolution llpGe or Si(l a) spectrometers. In Uie present investigations, photon attenuation cocftcicnls have been measured at energies around L < edge ol Pi 1 1 1 Pt-Rh alloy (80%, 20%) using synchrotron radiation facility at the Laboraton Nc/ionalc di Frascati. 1NFN, Frascati, Italy in order to see the possible alloying el I eelsThe details of the experimental set-up and the procedures ol scanning the spectra wete presented in an earlier publication by Parthasaradhi et al 14 ] . The speclia with and without Pi and Pt-Rh alloy foils are recorded. Subtracting Uie ln( i j i )  obtained without the samples from the one with the sample, the absolute spectra are obtained (/„ and /s aie cunenis ol Uie ionization chambers before and after the inclusion of samples respectively)In order to study the effect of alloying on the photon attenuation coefficient at L , edge in Pt, the following procedure has been followed : (1) The energy scale is normalised at the point of inflection with L3 edge energy (11564 eV) reported by Storm and Isiacl [5] BasedLaboratort Nazionale di Frascati, INFN. Frascati. Italy <y> 1995 (AC’S292 K Parthasaradhi, A Esposito, S Mobilio and M Pelliccionion this energy norm alization, the data o f  Pt-Rh alloy is norm alised. (2 ) T o study the absolute  attenuation coefficients, the spectra are norm alized  at about 6 7 0  eV  ab ove  the absorption edge energy  using the theoretical cross section s o f  S co fie ld  [6] and H ubbell and cow ork ers  [7 ,8 1; the procedure w hich has already been used in our earlier work |4 ] . A t these en erg ies , the oscillatory behaviour is significantly sm all. Such a norm alization procedure m in im ises theFigure 1. Photon mass attenuation coefficients afODnd edge of Pt and Pt from Pt-Rh (80%, 20%) alloy.error, particularly due to uncertainties in w eight, non-uniform ity o f  the fo ils , scattering and secondary fluorescent radiation e ffec ts  etc. (3 )  T he photon attenuation co e ffic ie n ts  o f  Pt are a lso  d ed u ced  from  th o se  m easured  in Pt-R h a llo y  by subtracting 20%  o f  the theoretical contribution o f  attenuation c o e ffic ie n t o f  Rh. The contribution is ca lcu lated  by adding the p h oto electr ic  cross sec tio n s o f  S c o fie ld  [6] and scattering cross sec tio n s o f  H ub bell and  co w ork ers [7 ,8 ] for Rh. The abso lu te  attenuation co effic ie n ts  o f  Pt m easured directly  and those dedu ced  from  the m easurem ents m ade in Pt-Rh a lloy  are com pared in F igure 1, in the region o f  ed g e  o f  Pt. T he d ifferen ce  b etw een  these  tw o data are a lso  sh ow n  in the sam e  figure. T h e  uncertainty in the m easured values is o f  the order o f  2% . It can be noted from  the figure that the d ifference in the tw o sets o f  data particularly at L y  adge is considerab le. It m ayPhoton attenuation coefficients hear /M edge ofPt  in PhRli alloy 293he noted that Storm and Israel |5) has given only one unique edge energy whereas Scofield (6) has given two edge energies 11555 eV (Lower) and I 1647 eV (Uppci) separated by 92 eV. These two energies ;ire below and above the edge energy of Storm and Israel |5|. In general, no alloying effect on the photon attenuation coefficient at these two energies o! Scofield 16) has been noticed. However, it may be noted Irum the figure that the alloying effect on the photon attenuation coeificient at the L; edge energy ol Storm and Israel |6| is of the order of 12%. Since the scattering contribution to the photon attenuation coellieient is small in this energy region the observed alloying effect can delmitely be attributed to the photoelectric process onlyR e fe r e n c e s|l] K Joga Kao, G Nagcswara Rao, B V Tirumala Kao. M L N Ra|ii K hemchand and K Puiihusaindhi I n d i a n  J  E u r e  A p p l  H i m  23 160(19X5)12 1 G Nagcswara Kao, K Joga Kao, B V Thiiumala, M 1,N Rapi and K Paiiliasaiadln H h \  \ AVi A3I M2 1(19X5) ^|3| B Seethaiaini Reddy, K Picmchand. P V Ramana Kao and K Pnrthasaiudlii I n d i a n  I E r n e  A f> /d  E h v s  29 641 (1992)|4] K Pailhasaiadln, A Esposito, S Mobiho and M Felliceioni E l i w  l< e v  A38 1608 ( |9XXj 151 H Sioi m and If 1 Israel N i k  t e a r  D a t a  T a b l e  A7 565 (1970)[6J J H Scofield ' f h e o r r t u a l  E l i n t o u m i : a t u m  < t a w  \ e i  H a n s  f i o n i  I l a  l ^ H )  K e V  U (  HI.  R c p t n l  5/ O f )  i 197?)(7] J H Hubbell, W Viegele. E A Briggs, R T Brown, D T Croner and R 1 Howerton J Phy\ Chem ReJ D a t a  4 471 (1975), E r r a t u m  6 615 (1977)[X] J II Hubbell and L Ovcrbo J E l i y s  C h e m  R e f  D a t a  8 69 (1979)

Photon Attenuation Coefficients Near L3 Edge of Pt in Pt-Rh Alloy

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Photon Attenuation Coefficients Near L3 Edge of Pt in Pt-Rh Alloy

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