Transmitted herewith are three copies of TEI-5^8, "An improved glass sample holder for assaying low radioactivity samples," lay F. J.

We present high resolution rovibrational spectra of buffer gas cooled vinyl bromide (C 2 H 3 Br) and nitromethane (CH 3 NO 2) in the 3 µm CH stretch region, acquired via cavity-enhanced direct frequency comb absorption spectroscopy. The ∼ 10 K translational and rotational temperatures of the molecular gas, as well as the narrow linewidth of the frequency comb, yield well resolved rotational structure, isotope shifts, and nuclear hyperfine splittings. Given the wide bandwidth of the light source and the long path length of the enhancement cavity, we measure entire vibrational bands in a single shot with high signal-to-noise ratios. We discuss spectra of the entire fundamental CH stretch manifolds of both C 2 H 3 Br and CH 3 NO 2 , which provide contrasting examples of rovibrational structure of rigid and non-rigid systems. C 2 H 3 Br is a relatively normal asymmetric top, exhibiting local perturbations to its rotational structure. Conversely, CH 3 NO 2 contains an essentially unhindered methyl rotor. Of particular interest are its quasi-degenerate asymmetric CH stretch modes. Here, one must consider multiple couplings between torsional, rotational, and vibrational angular momentum, leading to qualitatively new level patterns and structure.

We report infrared photodissociation spectra of [Bi(CO 2 ) n ] − (n = 2 − 9) cluster anions. We determine the charge carrier geometry by comparing calculated vibrational frequencies based on density functional theory to the experimental spectra. The vibrational frequencies and the charge carrier geometry depend strongly on the solvation environment present in the cluster. We discuss the interaction of bismuth and CO 2 in the presence of an excess electron in the context of heterogeneous catalytic reduction of CO 2 .

We present infrared photodissociation spectra of [Fe(CO 2 ) n ] − (n = 3 − 7) cluster anions. We use density functional theory to compare calculated vibrational frequencies to our experimental spectra to determine plausible structures for the molecular charge carriers. The spectra display similar characteristics to those of other complexes of first-row transition metals with CO 2 ligands, and show signatures of several structural motifs.

We present work on a prototypical water oxidation catalyst, namely the aqua-complex [(bpy)(tpy)Ru-OH 2 ] 2+ (2,2'bpy = bipyridine, tpy = 2,2':6',2"-terpyridine), and its hydrated clusters [(bpy)(tpy)Ru-OH 2 ] 2+ •(H2O) n , with n = 1-4. This complex is the starting species in a catalytic cycle for water oxidation. We couple electrospray ionization mass spectrometry with laser spectroscopy to circumvent challenges that arise in reactive solutions from speciation. Here, we report the electronic spectrum of [(bpy)(tpy)Ru-OH 2 ] 2+ by photodissociation spectroscopy of mass selected, cryogenically prepared ions, and we examine effects of its microhydration environment on its electronic structure. In particular, we investigate the solvatochromic shift of the spectral envelope upon sequential addition of water molecules up to the tetrahydrate.