Sam Lipoff is a doctoral student in the Technology and Operations Management unit at HBS. He is interested in science, technology and innovation dynamics, particularly the processes and conditions under which science becomes or does not become technology, and understanding how versions of technology based products relate to each other. Sam maintains a particular interest in China, speaks and reads Mandarin Chinese, and travels there several times a year. Sam is also particularly interested in business history.
Sam studied Chemistry and Physics and History of Science as an undergraduate at Harvard University, History and Philosophy of Science as an Mphil student at Trinity College, Cambridge, and Physical Chemistry as a graduate student at MIT. Sam has taught chemistry at Harvard, MIT, and to area high schools and local boy scouts. Sam has received Fulbright, NSF and DHS Fellowships, has worked at the US Department of Homeland Security, provided technical advice to private equity and venture capital firms on scientific subjects, and served as an expert witness on consumer electronics for patent litgation. Sam has published several papers in chemistry, physics, and electrical engineering, and holds US Utility Patent #7,110,118.
Sam serves on the board of the Massachusetts Future Problem Solving Program and the Harvard Project for Asian and International Relations.
Low-energy limit for tunnelling subject to an Eckart potential barrier
For two-body s-wave collisions subject to tunnelling though an Eckart potential barrier, cross-sections and rate coefficients in the low-energy regime can be evaluated in analytic form. These provide criteria for approach to the Wigner limit and a generic plot applicable to ultracold collisions (<1 mK). The Eckart barrier shape is found to fit fairly well accurate potential curves available for F(2P) + F(2P) and He(1S) + He*(1S). Also discussed are tunnelling-dominated ultracold chemical reactions, exemplified by F + H2. The very slow approach of the reactants allows averaging over rovibrational motions, so the effective adiabatic ('dressed') potential surface differs substantially from the Born–Oppenheimer ('bare') surface obtained from electronic structure calculations. The dressed barrier is more than two-fold lower and also thinner. For it the Eckart model gives an ultracold rate coefficient for forming HF in its v' = 2, j' = 0 rovibrational state (6.5 × 10−14 cm3/s) that is about 200-fold higher than for the bare barrier and of the same magnitude found from a full-scale 3-D quantum scattering calculation.