Atoms, Defects and Diffusion in Solids

Collins Research Group
Hyperfine Interactions Laboratory

Department of Physics and Astronomy, Washington State University, Pullman, WA, 99164-2814, USA
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Welcome!  We study the local structure of ordered solids using nuclear hyperfine interactions.  Interactions between quadrupole moments and electric field gradients (EFG) are used to "flag" local environments of radioactive probe atoms.  EFGs depend on crystal structure, lattice location, and whether or not there are neighboring point defects.  Signal amplitudes give site fractions of probes that can be used to determine defect concentrations as well as thermodynamic properties such as the enthalpies of probe atoms on different sites, formation and migration enthalpies of defects, and enthalpies of interaction between defects and probe atoms.   We particularly apply  perturbed angular correlation of gamma rays (PAC), and are the principal PAC group in North America studying solids.  We pioneered the use of PAC to study of diffusion of probe atoms jumping at frequencies in the MHz to GHz range, which gives rise to detectable nuclear relaxation.  We mostly study intermetallic compounds but methods are applicable to all classes of solids. 

Current interests:
We have also gained insight into experimental results with full-potential ab initio electronic structure calculations using the program WIEN2k .  Click below to learn more about PAC and to download papers.  Contact me for more information or to explore possible collaboration.

What we do
Who we are
PAC spectroscopy
Useful links
Research opportunities
Sources of support
Papers 2011-2015
Papers 2006-2010
 Papers 2001-2005
Papers 1995-2000
Selected publications to 1995
Research highlights and powerpoints
Meeting abstracts
PAC links worldwide

International Conference on Diffusion in Materials (DIMAT 2014)  Münster, Germany
International Conference on Hyperfine Interactions a (HFI/NQI 2014), Canberra, Australia,

February 2015.  Send comments and suggestions to Professor Gary S. Collins at collins at  There have been maybe 75000 visitors since 1998.  Material in this web site is based in part on work supported by the Metals Program of the National Science Foundation under Grant DMR 14-10159 and predecessor grants, for which we are most grateful.  Additional support comes from the Praveen Sinha Fund for Physics Research.  Any opinions, findings, and conclusions or recommendations expressed in these pages are those of the author(s) and do not necessarily reflect views of the National Science Foundation or of the Praveen Sinha Fund.  Copyright© Gary S. Collins, 1995 and later years.  Disclaimer.
Locations of 2000 web visitors over a one year period.