Through the use of resonant two-photon ionization spectroscopy, sharp predissociation thresholds have been identified in the spectra of CrO, MoO, RuO, and RhO. Similar thresholds have previously been used to measure the bond dissociation energies (BDEs) of many molecules that have a high density of vibronic states at the ground separated atom limit. A high density of states allows precise measurement of the BDE by facilitating prompt dissociation to ground state atoms when the BDE is exceeded. However, the number of states required for prompt predissociation at the thermochemical threshold is not well defined and undoubtedly varies from molecule to molecule. The ground separated atom limit generates 315 states for RuO, 252 states for RhO, and 63 states for CrO and MoO. Although comparatively few states derive from this limit for CrO and MoO, the observation of sharp predissociation thresholds for all four molecules nevertheless allows BDEs to be assigned as 4.863(3) eV (RuO), 4.121(3) eV (RhO), 4.649(5) eV (CrO), and 5.414(19) eV (MoO). Thermochemical cycles are used to derive the enthalpies of formation of the gaseous metal oxides and to obtain IE(RuO) = 8.41(5) eV, IE(RhO) = 8.56(6) eV, D0(Ru–O−) = 4.24(2) eV, D0(Cr–O−) = 4.409(8) eV, and D0(Mo–O−) = 5.243(20) eV. The mechanisms leading to prompt predissociation at threshold in the cases of CrO and MoO are discussed. Also presented is a discussion of the bonding trends for the transition metal oxides, which are compared to the previously measured transition metal sulfides.

The predissociation thresholds of the early transition metal boride diatomics (MB, M = Sc, Ti, V, Y, Zr, Nb, La, Hf, Ta, W) have been measured using resonant two-photon ionization (R2PI) spectroscopy, allowing for a precise assignment of the bond dissociation energy (BDE). No previous experimental measurements of the BDE exist in the literature for these species. Owing to the high density of electronic states arising from the ground and low-lying separated atom limits in these open d-subshell species, a congested spectrum of vibronic transitions is observed as the energy of the ground separated atom limit is approached. Nonadiabatic and spin−orbit interactions among these states, however, provide a pathway for rapid predissociation as soon as the ground separated atom limit is reached, leading to a sharp decrease in signal to background levels when this limit is reached. Accordingly, the BDEs of the early transition metal borides have been assigned as D 0 (ScB) 1.72(6) eV, D 0 (TiB) 1.956( 16) eV, D 0 (VB) 2.150( 16) eV, D 0 (YB) 2.057(3) eV, D 0 (ZrB) 2.573(5) eV, D 0 (NbB) 2.989(12) eV, D 0 (LaB) 2.086(18) eV, D 0 (HfB) 2.593(3) eV, D 0 (TaB) 2.700(3) eV, and D 0 (WB) 2.730(4) eV. Additional insight into the chemical bonding and electronic structures of these species has been achieved by quantum chemical calculations.

ObjectiveDetermine the detection rate from an expanded targeted early cytomegalovirus (CMV) testing program implemented from a large healthcare system (Intermountain Healthcare, IHC).Study DesignRetrospective review.SettingTertiary medical center.MethodsAn electronic system was modified to include indications for testing whenever a provider placed an order for CMV testing. A retrospective analysis of this database was performed.ResultsFrom March 1, 2021 to August 31, 2022, there were 3450 (8.8%) patients who underwent CMV testing out of 39,245 total live births within the IHC system. Since the formal implementation of this program in 2019, annual CMV testing has increased almost 10‐fold: 2668 CMV tests were performed in 2021 compared to 289 CMV tests in 2015. The most frequent indication for congenital CMV (cCMV) testing was small for gestational age (SGA) (68.2%), followed by macrocephaly (13.5%), an abnormal hearing test (5.0%), and microcephaly (4.4%). Fourteen cCMV‐infected infants were diagnosed all of them meeting the criteria for symptomatic cCMV. The most common indication resulting in a positive diagnosis was those who presented with SGA (n = 10 patients). The positivity rate would result in a prevalence of 35.7 symptomatic cCMV cases diagnosed per 100,000 live births, numbers comparable to those expected for universal cCMV screening.ConclusionAn expanded targeted early cCMV testing program may improve detection rates of symptomatic cCMV cases and should be considered as a feasible alternative approach to universal or hearing‐targeted early CMV testing.

Resonant two-photon ionization experiments have been conducted to probe the bond dissociation energy (BDE) of the lanthanide–carbon bond, allowing the BDEs of CeC, PrC, NdC, LuC, and Tm–C2 to be measured to high precision. Values of D 0(CeC) = 4.893(3) eV, D 0(PrC) = 4.052(3) eV, D 0(NdC) = 3.596(3) eV, D 0(LuC) = 3.685(4) eV, and D 0(Tm–C2) = 4.797(6) eV are obtained. Additionally, the adiabatic ionization energy of LuC was measured, giving IE­(LuC) = 7.05(3) eV. The electronic structure of these species, along with the previously measured LaC, has been further investigated using quantum chemical calculations. Despite LaC, CeC, PrC, and NdC having ground electronic configurations that differ only in the number of 4f electrons present and have virtually identical bond orders, bond lengths, fundamental stretching frequencies, and metallic oxidation states, a peculiar 1.30 eV range in bond dissociation energies exists for these molecules. A natural bond orbital analysis shows that the metal atoms in these molecules have a natural charge of +1 with a 5d2 4f n 6s0 configuration while the carbon atom has a natural charge of −1 and a 2p3 configuration. The diabatic bond dissociation energies, calculated with respect to the lowest energy level of this separated ion configuration, show a greatly reduced energy range of 0.32 eV, with the diabatic BDE decreasing as the amount of 4f character in the σ-bond increases. Thus, the wide range of measured BDEs for these molecules is a consequence of the variation in atomic promotion energies at the separated ion limit. TmC2 has a smaller BDE than the other LnC2 molecules, due to the tiny amount of 5d participation in the valence molecular orbitals.

The predissociation threshold of VO has been measured using resonant three-photon ionization (R3PI) spectroscopy. Given the high density of electronic states in the molecule, it is argued that the molecule dissociates rapidly as soon as the thermochemical bond dissociation energy (BDE) is exceeded, allowing the measured predissociation threshold to be assigned as the BDE. This is the first time a BDE has been measured using the R3PI method. The first photon is provided by an optical parametric oscillator (OPO) laser that promotes VO into a high-energy, discrete vibronic state. A tunable dye laser then excites the molecule further to a resonant state close to the dissociation limit where there is a quasi-continuum of states. A second photon from the same dye laser pulse ionizes the molecule, generating VO+ ions. The dye laser is then scanned to higher energies, and when the energy of one OPO photon plus one dye photon exceeds the BDE, the molecule dissociates before another dye photon can be absorbed to induce ionization. The combined photon energy at the sharp drop in the ion signal is assigned as the BDE. The experiment has been repeated using four different intermediate states, all yielding the same BDE, D0(VO) = 6.545(2) eV. Using thermochemical cycles, a revised value for the BDE of cationic VO is obtained, D0(V+–O) = 6.053(2) eV. The 0 K enthalpy of formation for VO(g) is also derived as ΔfH0K0VO(g) = 128.6(1.0) kJ mol−1. Previous spectroscopic and thermochemical studies of VO are reviewed.