“…This method was introduced by Batterman and Golovchenko and co-workers in several classic papers (Batterman, 1964(Batterman, , 1969Golovchenko et al ., 1974;Cowan et al ., 1980) that pointed out the utility of both long-period and short-period (or Bragg) XSW-FY spectroscopy for probing the distribution of metal ions at buried interfaces . Subsequently, the long-period XSW-FY (LP-XSW-FY) method has been used to probe the vertical distribution of atoms at a number of different types of interfaces, including electrochemical interfaces (Bedzyk et al ., 1986;Abruna et al ., 1990); biological membranes (Bedzyk et al ., 1988(Bedzyk et al ., , 1989(Bedzyk et al ., , 1990Wang et al ., 1991Wang et al ., , 2001, organic thin films (Bedzyk, 1992), mineral-water interfaces (Trainor et al ., 2002a;Levard et al ., 2011b) and mineral surfaces coated with microbial biofilms or thin organic films (Templeton et al ., 1999(Templeton et al ., , 2001(Templeton et al ., , 2003bYoon et al ., 2005a) . Bedzyk and Cheng (2002) and Trainor et al (2006) provide excellent reviews of these various applications of LP-XSW-FY spectroscopy through 2006 .…”