Double resonance spectroscopy reveals structure and dynamics near transition states.

A shared ambition of molecular spectroscopy and molecular dynamics is to establish the truths of chemical intuition on solid physical bedrock. Experimental characterization of the transition state was thought unattainable, but modern techniques have begun to achieve the incredible.

Significantly Improved Detection of Molecular Oxygen by Two-Color Resonance-Enhanced Multiphoton Ionization.

We report a new spectroscopic detection scheme for molecular oxygen that achieves roughly two orders of magnitude higher sensitivity for fully rotationally resolved spectra than the current state of the art. Two-color (2 + 1') resonance-enhanced multiphoton ionization (REMPI) via the 3 Rydberg complex yields state-selective spectra with signal comparable to the intense but diffuse 3σ Π ← Σ (2 + 1) REMPI bands without significant saturation or broadening. The resulting increase in sensitivity permitted observation of the very weak 3π Δ ← Σ transitions and is independent of the intermediate state.

Thermochemical Studies of Small Carbohydrates.

Despite their prevalence in biomass and importance in biochemistry, there is still much to be learned about simple carbohydrates. Gas-phase calculations are reported here on two trioses and three tetroses. For aldotetroses, both the open-chain and furanose forms are considered.

Latency for All: Enabling Latency of Hoveyda-Grubbs Second-Generation Catalysts by Adding Phosphite Ligands.

The Hoveyda-Grubbs catalyst (, M720 Umicore) is among the most widely used catalysts in olefin metathesis reactions. Given the usefulness of and the great interest in developing latent olefin metathesis catalysts for numerous applications, we developed a method to introduce phosphite molecules as ancillary ligands into the precatalyst framework. This modification alters the geometry of the complex from an active -dichloro form to a latent -dichloro species.

Shining Light on Photobleaching: An Artifact That Causes Unnecessary Excitation Among Pathologists.

Context.—: Photobleaching artifact occurs when fluorescence intensity decreases following light exposure. Slides stained with fluorescent techniques may be stored in the dark until primary diagnostics.