Obituary of Samuel Francisco Treviño

Sam Treviño was born in San Antonio, TX where he graduated from St. Mary’s University in 1958. He received a Ph. D. in nuclear physics from the University of Notre Dame in 1964, and entered the Army in late1963, serving two years at the Watertown (MA) Arsenal where the Army had established a new research program utilizing neutrons from the Arsenal’s 2 MW research reactor. Sam attained the rank of captain, and immediately after leaving the Army was hired by Picatinny (NJ) Arsenal as a research physicist. He worked for Picatinny Arsenal, later known as the U.S. Army Armament R, D & E Center, from 1965 until 1996. He transferred to the Army Research Lab in Aberdeen, MD where he was employed until his retirement in 2005. From 1970 until his death Sam worked at the Center for Neutron Research of the National Institute of Standards and Technology (NIST), formerly NBS, in Gaithersburg, MD.

In the early part of his Army research career Sam became intrigued by low-energy neutron scattering as a tool for the study of condensed matter. Along with studies of “energetic materials” such as metal azides, ammonium nitrate and ammonium perchlorate, Sam become very interested in low frequency vibrational modes in polymers. This led to important studies of many polymers, including oriented polyethylene and Teflon®;. Concurrent with this work, Sam focused on understanding what neutron inelastic scattering revealed, contrasting it with other spectroscopies. This led him to very productive and important collaborations first with K. R. Rao, then with R. C. Casella in which inelastic neutron scattering “selection rules” were developed using group theory.

In the ‘70s Sam led many studies of solids containing the molecular groups sodium nitrate, benzene, and deuterium peroxide. This work culminated in a series of studies of nitromethane which spanned the 1980’s and became a recognized classic in the study of internal rotation of methyl groups in molecular solids. Sam, with a number of collaborators, determined the crystal structure, details of the methyl reorientations, the tunnel splitting, and the pressure dependence of the torsional levels. Also in the 80’s Sam began a very productive collaboration with D. H. Tsai in which molecular dynamics modeling was used for the first time to simulate molecular dissociation and the initiation of detonation in simple molecular solids. After Tsai’s retirement Sam continued work in this area throughout the'90’s with B. M. Rice.

In the 90’s Sam returned to polymers. With N. B. Tan and others, several important studies of a variety of copolymers were completed with small-angle neutron scattering as the key probe. Studies of micelles, microemulsions, and Nafion® were performed in the late ‘90s and beyond. Sam’s last published research was with J. A. Ciezak in which inelastic neutron scattering studies were performed on organic solids composed of very complex molecules. The very last of these was on solid cyclotrimethylenetrinitramine, also known as RDX, one of the first materials Sam studied when first hired by Picatinny Arsenal, 40 years earlier.

In addition to the research outlined above, Sam, along the way, found the time to lead in the development of two important neutron spectrometers, develop a high pressure system for neutron studies and to become an expert in “squeezing” monochromator crystals in order to significantly increase the mosaic spread and diffracted-beam intensity. These efforts benefited hundreds of users of NIST’s neutron facilities. He also collaborated on the first measurements in which “depth-profiling” was successfully utilized in an “engineering” application of neutron diffraction.

Over the course of his career Sam received a number of awards and honors from the Army, including the first Paul A. Siple Award for outstanding, new research. His research was recognized internationally through invited papers and invitations to chair sessions at conferences. His international recognition was also manifested by the amazing number and diversity of scientists, worldwide, with whom he collaborated.He loved teaching and working with young researchers and took a part-time teaching position in the Physics, Engineering&Geosciences Dept. at Montgomery College ( Rockville, MD) beginning in 1991 and lasting until his death.

He was devoted to his wife of forty-nine years, Juliette, and to their five children and eleven grandchildren. He was active in the community, working for many years with youth groups. He loved music of all types, and literature, especially the works of South American writers such as Gabriel Garcia Márquez.

Sam will be remembered for his love of physics, his love of teaching, his infectious enthusiasm, his ready laugh, and his love of people.