Tilting Toward Reaction: Collisions between molecules and metal surfaces underlie many of the catalytic pathways that transform natural feedstocks into fuels and commodity chemical compounds. One such reaction, in which nickel strips hydrogen from methane, depends on whether the methyl C-H bonds are vibrating just before the molecule strikes the surface. Yoder et al. (p. 553 ) now delve deeper into this system. By aligning incoming molecular samples using polarized infrared light, they show that the hydrocarbon reacts most readily when it is vibrating parallel, rather than perpendicular, to the surface.

The knowledge of optical properties of tungsten at high temperatures is of crucial importance in fields such as nuclear fusion and aerospace applications. The optical properties of tungsten are well known at room temperature, but little has been done at temperatures between 300 K and 1000 K in the visible and near-infrared domains. Here, we investigate the temperature dependence of tungsten reflectivity from the ambient to high temperatures (<1000 K) in the 500–1050 nm spectral range, a region where interband transitions make a strong contribution. Experimental measurements, performed via a spectroscopic system coupled with laser remote heating, show that tungsten’s reflectivity increases with temperature and wavelength. We have described these dependences through a Fresnel and two Lorentz–Drude models. The Fresnel model accurately reproduces the experimental curve at a given temperature, but it is able to simulate the temperature dependency of reflectivity only thanks to an ad hoc choice of temperature formulae for the refractive indexes. Thus, a less empirical approach, based on Lorentz–Drude models, is preferred to describe the interaction of light and charge carriers in the solid. The first Lorentz–Drude model, which includes a temperature dependency on intraband transitions, fits experimental results only qualitatively. The second Lorentz–Drude model includes in addition a temperature dependency on interband transitions. It is able to reproduce the experimental results quantitatively, highlighting a non-trivial dependence of interband transitions as a function of temperature. Eventually, we use these temperature dependent Lorentz–Drude models to evaluate the total emissivity of tungsten from 300 K to 3500 K, and we compare our experimental and theoretical findings with previous results.

Reflection absorption infrared spectroscopy (RAIRS) was used to probe for vibrational bond-selectivity in the dissociative chemisorption of three partially deuterated methane isotopologues on a Pt(111) surface. While a combination of incident translational energy and thermal vibrational excitation produces a nearly statistical distribution of C–H and C–D bond cleavage products, we observe that laser excitation of an infrared active C–H stretch normal mode leads to highly selective dissociation of a C–H bond for CHD₃, CH₂D₂, and CH₃D. Our results show that vibrational energy redistribution between C–H and C–D stretch modes due to methane/surface interactions is negligible during the sub-picosecond collision time which indicates that vibrational bond-selectivity may be the rule rather than the exception in heterogeneous reactions of small polyatomic molecules.