A combination band due to a mechanism whereby a photon excites two or more vibrational modes (e.g. a bend and a stretch) of an individual molecule is commonly seen in laboratory and astronomical spectroscopy. Here, we present evidence of a much less commonly seen combination band − one where a photon simultaneously excites two adjacent molecules in an ice. In particular, we present nearinfrared spectra of laboratory CO/N 2 ice samples where we identify a band at 4467.5 cm −1 (2.239 µm) that results from single photons exciting adjacent pairs of CO and N 2 molecules. We also present a near-infrared spectrum of Neptune's largest satellite Triton taken with the Gemini-South 8.1 meter telescope and the Immersion Grating Infrared Spectrograph (IGRINS) that shows this 4467.5 cm −1 (2.239 µm) CO-N 2 combination band. The existence of the band in a spectrum of Triton indicates that CO and N 2 molecules are intimately mixed in the ice rather than existing as separate regions of pure CO and pure N 2 deposits. Our finding is important because CO and N 2 are the most volatile species on Triton and so dominate seasonal volatile transport across its surface. Our result will place constraints on the interaction between the surface and atmosphere of Triton.

In this investigation, thermal vapor deposition was used to synthesize films of polyvinylidene fluoride (PVDF) containing nanoparticles of the ceramic titanium dioxide (TiO2). This ferroelectric polymer has shown promise as a capacitor dielectric material with possible enhanced electrical properties when combined with ceramic nanoparticles. The films were synthesized starting from a mixture of PVDF and TiO2 (rutile phase) dissolved in dimethylformamide (DMF) solvent. The PVDF-TiO2 mixture was vapor deposited onto a Si wafer. The temperature during the deposition was approximately 400 °C and the deposition time was 15 min. The deposited films were characterized using x-ray photoelectron spectroscopy (XPS). It is noted that various starting mixtures and deposition parameters were investigated. The spectra reported here are from films from two different initial PVDF/TiO2 mixtures (prior to deposition). For the maximum concentration of TiO2 in the deposited films, the Ti atomic concentration is just under 10%. Analysis from XPS shows a defluorination of the films (C/F ratio >1) from the deposition process, with the final film being a mixture of PVDF and polyvinyl fluoride (PVF). It is also noted that energy dispersive spectroscopy (EDS) and atomic force microscopy (AFM) show that the TiO2 nanoparticles are homogeneously distributed in the films. The reported XPS spectra include survey and high resolution scans of the major photoelectron peaks.