New Infrared Spectra of the Water-CO Complex: Determination of Four Intermolecular Modes and Test of a High-Level Potential Energy Surface.

High resolution infrared spectra of water-CO dimers are further studied using tunable infrared sources to probe a pulsed slit jet supersonic expansion. The relatively weak transition of DO-CO in the DO ν fundamental region (≈2760 cm) is observed for the first time, as are various spectra of DO-CO. Combination bands involving the intermolecular in plane geared bend (disrotatory) mode are observed for HO-CO (≈1642, 2397 cm) in the HO ν and CO ν regions, for HDO-CO (≈2761 cm) in the HDO ν region, and for DO-CO (≈2386, 2705 and 2821 cm) in the CO ν, DO ν, and DO ν regions.

Progress in understanding the infrared spectrum of the H2O-O2 dimer.

Spectra of the weakly bound H2O-O2 dimer are studied in the region of the H2O ν2 band using a tunable quantum cascade laser to probe a pulsed supersonic slit jet expansion. These are the first gas-phase infrared spectra of H2O-O2 and among only a few such results for O2-containing complexes. Almost 100 infrared lines are assigned based on the ground state combination differences from the microwave spectrum of H2O-O2.

New Infrared Spectra of Acetylene-Water Dimers: First Determination of the Rotational Constant and Another -Dependent Anomaly.

Infrared spectra of acetylene-water complexes are studied in the regions of the HO ν bend (1600 cm) and the DO ν/ν stretches (2670-2808 cm), using tunable infrared sources to probe a pulsed supersonic slit jet expansion. In the HO bend region, there is a puzzling absence of = 0 transitions for CH-HO, while both = 0 and 1 are observed for CD-HO. This continues a pattern of "missing" states noted in previous infrared studies of acetylene-water.

Water-carbon disulfide dimers: observation of a new isomer and structure theory.

The weakly bound dimer water-carbon disulfide is studied by structure theory and high-resolution infrared spectroscopy. The calculations yield three stable minima in the potential energy surface, all planar. The most stable, isomer 1, was observed previously by microwave spectroscopy.

Infrared spectra of partially deuterated water dimers in the fundamental O-D stretch region.

Spectra of mixed H/D water dimers are studied in the mid-infrared region of the O-D stretch fundamental (2630-2800 cm-1) using a pulsed supersonic slit jet and a tunable optical parametric oscillator infrared source. Over 30 bands, belonging to nine of the ten possible isotopologues (only H2O-HOD is missed), are observed and analyzed. The implications for excited state tunneling splittings, lifetime effects, and vibrational shifts are discussed.

Spectra of the D2O dimer in the O-D fundamental stretch region: The acceptor symmetric stretch fundamental and new combination bands.

The O-D stretch fundamental region of the deuterated water dimer, (D2O)2, is further studied using a pulsed supersonic slit jet and a tunable optical parametric oscillator infrared source. The previously unobserved acceptor symmetric O-D stretch fundamental vibration is detected, with Ka = 0 ← 0 and 1 ← 0 sub-bands at about 2669 and 2674 cm-1, respectively. The analysis indicates that the various water dimer tunneling splittings generally decrease in the excited vibrational state, similar to the three other previously observed O-D stretch fundamentals.

First-ever satellite tracking of Black Terns (): Insights into home range and habitat selection.

Understanding animal movement across the annual cycle is critical for developing appropriate conservation plans, but the large size and high cost of tracking devices can limit the spatial and temporal resolution at which movement data can be collected, especially for small avian species. Furthermore, for species with low breeding site fidelity, the ability to obtain tracking data from small, archival tags is hindered by low recapture rates. We deployed satellite tracking devices on four adult Black Terns (), a declining waterbird with low site fidelity, to examine space use and selection of resources within individual breeding home ranges.

Infrared Spectra of the Water-CO Complex in the 4.3-3.6 μm Region and Determination of the Ground State Tunneling Splitting for HDO-CO.

Spectra of water─CO dimers are studied using a tunable mid-infrared source to probe a pulsed slit jet supersonic expansion. HO-CO and DO-CO are observed in the CO ν fundamental region (≈2350 cm), DO-CO is also observed in the DO ν fundamental region (≈2790 cm), and HDO-CO is observed in the HDO O-D stretch fundamental region (≈2720 cm), all for the first time in these regions. Analysis of the spectra yields excited state rotational parameters and vibrational shifts.

Doped rare gas clusters up to completion of first solvation shell, CO-(Rg), n = 3-17, Rg = Ar, Kr, Xe.

Spectra of rare gas atom clusters containing a single carbon dioxide molecule are observed using a tunable mid-infrared (4.3 µm) source to probe a pulsed slit jet supersonic expansion. There are relatively few previous detailed experimental results on such clusters.

Spectra of CO-Rg and CO-Rg-He trimers (Rg = Ne, Ar, Kr, and Xe): Intermolecular CO rock, vibrational shifts and three-body effects.

Weakly bound CO-Rg trimers are studied by high-resolution (0.002 cm) infrared spectroscopy in the region of the CO ν fundamental band (≈2350 cm), using a tunable optical parametric oscillator to probe a pulsed supersonic slit jet expansion with an effective rotational temperature of about 2 K. CO-Ar spectra have been reported previously, but they are extended here to include Rg = Ne, Kr, and Xe as well as new combination and hot bands.

A general deep learning model for bird detection in high-resolution airborne imagery.

Advances in artificial intelligence for computer vision hold great promise for increasing the scales at which ecological systems can be studied. The distribution and behavior of individuals is central to ecology, and computer vision using deep neural networks can learn to detect individual objects in imagery. However, developing supervised models for ecological monitoring is challenging because it requires large amounts of human-labeled training data, requires advanced technical expertise and computational infrastructure, and is prone to overfitting.

Weakly-bound clusters of atmospheric molecules: infrared spectra and structural calculations of (CO)-(CO)-(N), (,,) = (2,1,0), (2,0,1), (1,2,0), (1,0,2), (1,1,1), (1,3,0), (1,0,3), (1,2,1), (1,1,2).

Structural calculations and high-resolution infrared spectra are reported for trimers and tetramers containing CO together with CO and/or N. Among the 9 clusters studied here, only (CO)-CO was previously observed by high-resolution spectroscopy. The spectra, which occur in the region of the fundamental of CO (≈2350 cm), were recorded using a tunable optical parametric oscillator source to probe a pulsed supersonic slit jet expansion.

Exploring the next step in micro-solvation of CO in water: Infrared spectra and structural calculations of (HO)-CO and (DO)-CO.

We extend studies of micro-solvation of carbon monoxide by a combination of high-resolution IR spectroscopy and ab initio calculations. Spectra of the (HO)-CO and (DO)-CO pentamers are observed in the C-O stretch fundamental region (≈2150 cm). The HO containing spectrum is broadened by predissociation, but that of DO is sharp, enabling detailed analysis that gives a precise band origin and rotational parameters.

Symmetry breaking of the bending mode of CO in the presence of Ar.

The weak infrared spectrum of CO2-Ar corresponding to the (0111) ← (0110) hot band of CO2 is detected in the region of the carbon dioxide ν3 fundamental vibration (≈2340 cm-1), using a tunable OPO laser source to probe a pulsed supersonic slit jet expansion. While this method was previously thought to cool clusters to the lowest rotational states of the ground vibrational state, here we show that under suitable jet expansion conditions, sufficient population remains in the first excited bending mode of CO2 (1-2%) to enable observation of vibrationally hot CO2-Ar, and thus to investigate the symmetry breaking of the intramolecular bending mode of CO2 in the presence of Ar. The bending mode of the CO2 monomer splits into an in-plane and an out-of-plane mode, strongly linked by a Coriolis interaction.

Spectra of CO-N dimer in the 4.2 μm region: Symmetry breaking of the intramolecular CO bend, the intermolecular bend, and higher K-values for the fundamental.

Infrared spectra of the CO-N dimer are observed in the carbon dioxide ν asymmetric stretch region (≈2350 cm) using a tunable infrared optical parametric oscillator to probe a pulsed slit jet supersonic expansion. Previous results for the b-type fundamental band are extended to higher values of K. An a-type combination band involving the lowest in-plane intermolecular bending mode is observed.

The Ethylene-Carbon Dioxide Complex and the Double Rotor Model.

The infrared spectrum of the weakly bound CH-CO complex is investigated in the region of the ν fundamental band of CO (≈2350 cm), using a tunable OPO laser source to probe a pulsed supersonic slit jet expansion. The spacing of the various -subbands in this perpendicular (Δ = ±1) spectrum is very irregular, and the pattern of irregularity is quite different from that observed previously in another CH-CO band by Bemish et al. [ 1995 , 103 , 7788 ].

Micro-solvation of CO in water: infrared spectra and structural calculations for (DO)-CO and (DO)-CO.

The weakly-bound molecular clusters (D2O)2-CO and (D2O)3-CO are observed in the C-O stretch fundamental region (≈2150 cm-1), and their rotationally-resolved infrared spectra yield precise rotational parameters. The corresponding H2O clusters are also observed, but their bands are broadened by predissociation, preventing detailed analysis. The rotational parameters are insufficient in themselves to determine cluster structures, so ab initio calculations are employed, and good agreement between the experiment and theory is found for the most stable cluster isomers, yielding the basic cluster geometries as well as confirming the assignments to (D2O)2-CO and (D2O)3-CO.

Long-distance migratory shorebirds travel faster towards their breeding grounds, but fly faster post-breeding.

Long-distance migrants are assumed to be more time-limited during the pre-breeding season compared to the post-breeding season. Although breeding-related time constraints may be absent post-breeding, additional factors such as predation risk could lead to time constraints that were previously underestimated. By using an automated radio telemetry system, we compared pre- and post-breeding movements of long-distance migrant shorebirds on a continent-wide scale.

The water-carbon monoxide dimer: new infrared spectra, ab initio rovibrational energy level calculations, and an interesting in-termolecular mode.

Bound state rovibrational energy level calculations using a high-level intermolecular potential surface are reported for H2O-CO and D2O-CO. They predict the ground K = 1 levels to lie about 20 (12) cm-1 above K = 0 for H2O-CO (D2O-CO) in good agreement with past experiments. But the first excited K = 1 levels are predicted to lie about 3 cm-1 below their K = 0 counterparts in both cases.

Spectra of the DO dimer in the O-D fundamental stretch region: Vibrational dependence of tunneling splittings and lifetimes.

The fundamental O-D stretch region (2600-2800 cm) of the fully deuterated water dimer (DO) is studied using a pulsed supersonic slit jet source and a tunable optical parametric oscillator source. Relatively high spectral resolution (0.002 cm) enables all six dimer tunneling components to be observed, in most cases, for the acceptor asymmetric O-D stretch, the donor free O-D stretch, and the donor bound O-D stretch vibrations.

Infrared bands of CS dimer and trimer at 4.5 μm.

We report observation of new infrared bands of (CS) and (CS) in the region of the CS ν + ν combination band (at 4.5 µm) using a quantum cascade laser. The complexes are formed in a pulsed supersonic slit-jet expansion of a gas mixture of carbon disulfide in helium.

Infrared spectrum and intermolecular potential energy surface of the CO-O dimer.

Only a few weakly-bound complexes containing the O2 molecule have been characterized by high resolution spectroscopy, no doubt due to the complications added by the oxygen molecule's unpaired electron spin. Here we report an extensive infrared spectrum of CO-O2, observed in the CO fundamental band region using a tunable quantum cascade laser to probe a pulsed supersonic jet expansion. The rotational energy level pattern derived from the spectrum consists of stacks of levels characterized by the total angular momentum, J, and its projection on the intermolecular axis, K.

Ultrafast Dissociation of Metastable CO^{2+} in a Dimer.

We triply ionize the van der Waals bound carbon monoxide dimer with intense ultrashort pulses and study the breakup channel (CO)_{2}^{3+}→C^{+}+O^{+}+CO^{+}. The fragments are recorded in a cold target recoil ion momentum spectrometer. We observe a fast CO^{2+} dissociation channel in the dimer, which does not exist for the monomer.

Five intermolecular vibrations of the CO dimer observed via infrared combination bands.

The weakly bound van der Waals dimer (CO) has long been of considerable theoretical and experimental interest. Here, we study its low frequency intermolecular vibrations by means of combination bands in the region of the CO monomer ν fundamental (≈2350 cm), which are observed using a tunable infrared laser to probe a pulsed supersonic slit jet expansion. With the help of a recent high level ab initio calculation by Wang, Carrington, and Dawes, four intermolecular frequencies are assigned: the in-plane disrotatory bend (22.