Quantum interference in atom-exchange reactions.

Chemical reactions, in which bonds break and form, are highly dynamic quantum processes. A fundamental question is whether coherence can be preserved in chemical reactions and then harnessed to generate entangled products. Here we investigated this question by studying the 2KRb [Formula: see text][Formula: see text] + Rb reaction at 500 nanokelvins, focusing on the nuclear spin degrees of freedom.

High-Resolution Photoelectron Spectroscopy of Vibrationally Excited Vinoxide Anions.

High-resolution photoelectron spectra of vibrationally pre-excited vinoxide anions (CHCHO) are reported using the recently developed IR-cryo-SEVI technique. This method is combined with a newly developed implementation of vibrational perturbation theory that can readily identify relevant anharmonic couplings among nearly degenerate vibrational states. IR-cryo-SEVI spectra are obtained by resonant infrared excitation of vinoxide anions via the fundamental C-O (ν, 1566 cm) or isolated C-H (ν, 2540 cm) stretching vibrations prior to photodetachment.

Observation of resonances in the transition state region of the F + NH reaction using anion photoelectron spectroscopy.

The transition state of a chemical reaction is a dividing surface on the reaction potential energy surface (PES) between reactants and products and is thus of fundamental interest in understanding chemical reactivity. The transient nature of the transition state presents challenges to its experimental characterization. Transition-state spectroscopy experiments based on negative-ion photodetachment can provide a direct probe of this region of the PES, revealing the detailed vibrational structure associated with the transition state.

High Resolution Photoelectron Spectroscopy of the Acetyl Anion.

High-resolution photoelectron spectra of cryogenically cooled acetyl anions (CHCO) obtained using slow photoelectron velocity-map imaging are reported. The high resolution of the photoelectron spectrum yields a refined electron affinity of 0.4352 ± 0.

Photoelectron spectroscopy of cryogenically cooled NiO slow photoelectron velocity-map imaging.

High-resolution anion photoelectron spectra of cryogenically cooled NiO anions, obtained using slow photoelectron velocity-map imaging (cryo-SEVI), are presented in tandem with coupled cluster electronic structure calculations including relativistic effects. The experimental spectra encompass the X̃Σ ← X̃Π, ãΠ ← X̃Π, and ÃΠ ← X̃Π photodetachment transitions of linear ONiO, revealing previously unobserved vibrational structure in all three electronic bands. The high-resolution afforded by cryo-SEVI allows for the extraction of vibrational frequencies for each state, consistent with those previously measured in the ground state and in good agreement with scalar-relativistic coupled-cluster calculations.

Structural Characterization of Nickel-Doped Aluminum Oxide Cations by Cryogenic Ion Trap Vibrational Spectroscopy.

Isolated nickel-doped aluminum oxide cations (NiO)(AlO)(AlO) with = 1-2 and = 1-3 are investigated by infrared photodissociation (IRPD) spectroscopy in combination with density functional theory and the single-component artificial force-induced reaction method. IRPD spectra of the corresponding He-tagged cations are reported in the 400-1200 cm spectral range and assigned based on a comparison to calculated harmonic IR spectra of low-energy isomers. Simulated spectra of the lowest energy structures generally match the experimental spectra, but multiple isomers may contribute to the spectra of the = 2 series.

Electronic structure of NdO via slow photoelectron velocity-map imaging spectroscopy of NdO.

Electronically excited NdO is a possible product of the chemistry associated with the release of Nd into the ionosphere, and emission from these states may contribute to the observations following such experiments. To better characterize the energetics and spectroscopy of NdO, we report a combined experimental and theoretical study using slow photoelectron velocity-map imaging spectroscopy of cryogenically cooled NdO anions (cryo-SEVI) supplemented by wave function-based quantum-chemical calculations. Using cryo-SEVI, we measure the electron affinity of NdO to be 1.

High-Resolution Photoelectron Spectroscopy of Vibrationally Excited OH.

The effect of vibrational pre-excitation of anions on their photoelectron spectra is explored, combining slow photoelectron velocity-map imaging of cryogenically cooled anions (cryo-SEVI) with tunable IR radiation to pre-excite the anions. This new IR cryo-SEVI method is applied to OH as a test system, where the R(0) transition of the hydroxyl anion (3591.53 cm) is pumped.

Unveiling the coexistence of cis- and trans-isomers in the hydrolysis of ZrO: A coupled DFT and high-resolution photoelectron spectroscopy study.

High-resolution anion photoelectron spectroscopy of the ZrOH and ZrOD anions and complementary electronic structure calculations are used to investigate the reaction between zirconium dioxide and a single water molecule, ZrO + HO. Experimental spectra of ZrOH and ZrOD were obtained using slow photoelectron velocity-map imaging of cryogenically cooled anions, revealing the presence of two dissociative adduct conformers and yielding insight into the vibronic structure of the corresponding neutral species. Franck-Condon simulations for both the cis- and trans-dihydroxide structures are required to fully reproduce the experimental spectrum.

High-Resolution Photoelectron Spectroscopy of Cryogenically Cooled NO̅.

High-resolution anion photoelectron spectra of cryogenically cooled NO̅ anions obtained using slow photoelectron velocity-map imaging are presented and provide new insight into the vibronic structure of the corresponding neutral radical. A combination of improved spectral resolution, measurement of energy-dependent intensity effects, temperature control, and comparison to theory allows for full assignment of the vibronic features observed in this spectrum. We obtain a refined electron affinity of 3.

Photoelectron spectra of AlO and AlOvia slow electron velocity-map imaging.

High-resolution photoelectron spectra of cryogenically-cooled Al2O2- and Al3O3- cluster anions are obtained using slow electron velocity-map imaging. These spectra show vibrationally-resolved detachment from the (X[combining tilde]2B3u) ground state of Al2O2- to the X[combining tilde]1Ag and ã3B3u neutral electronic states, giving an electron affinity of 1.87904(4) eV for neutral Al2O2 and a term energy of 0.

Slow photoelectron velocity-map imaging of cold and .

High-resolution anion photoelectron spectra of cryogenically cooled C and C clusters obtained using slow photoelectron velocity-map imaging are presented, providing insight into the vibronic structure of neutral C and C. These spectra yield accurate measurements of vibrational frequencies for the neutral clusters as well as electron affinities of 3.3517(4) and 3.

High-resolution photoelectron spectroscopy of TiOH: Probing the TiO + HO dissociative adduct.

Slow electron velocity-map imaging spectroscopy of cryogenically cooled TiOH anions is used to probe the simplest titania/water reaction, TiO + HO. The resultant spectra show vibrationally resolved structure assigned to detachment from the cis-dihydroxide TiO(OH) geometry based on density functional theory calculations, demonstrating that for the reaction of the anionic TiO monomer with a single water molecule, the dissociative adduct (where the water is split) is energetically preferred over a molecularly adsorbed geometry. This work represents a significant improvement in resolution over previous measurements, yielding an electron affinity of 1.

Autodetachment from Vibrationally Excited Vinylidene Anions.

Slow electron velocity-map imaging of the cryogenically cooled HCC¯ anion reveals a strong dependence of its high-resolution photoelectron spectrum on detachment photon energy in two specific ranges, from 4000 to 4125 cm and near 5020 cm. This effect is attributed to vibrational excitation of the anion followed by autodetachment to HCC + e¯. In the lower energy range, the electron kinetic energy (eKE) distributions are dominated by two features that occur at constant eKEs of 114(3) and 151.

Encoding of vinylidene isomerization in its anion photoelectron spectrum.

Vinylidene-acetylene isomerization is the prototypical example of a 1,2-hydrogen shift, one of the most important classes of isomerization reactions in organic chemistry. This reaction was investigated with quantum state specificity by high-resolution photoelectron spectroscopy of the vinylidene anions HCC- and DCC- and quantum dynamics calculations. Peaks in the photoelectron spectra are considerably narrower than in previous work and reveal subtleties in the isomerization dynamics of neutral vinylidene, as well as vibronic coupling with an excited state of vinylidene.

Feshbach resonances in the exit channel of the F + CHOH → HF + CHO reaction observed using transition-state spectroscopy.

The transition state governs how chemical bonds form and cleave during a chemical reaction and its direct characterization is a long-standing challenge in physical chemistry. Transition state spectroscopy experiments based on negative-ion photodetachment provide a direct probe of the vibrational structure and metastable resonances that are characteristic of the reactive surface. Dynamical resonances are extremely sensitive to the topography of the reactive surface and provide an exceptional point of comparison with theory.

Slow photoelectron velocity-map imaging of cold tert-butyl peroxide.

Photoelectron spectra of cryogenically cooled X∼A' tert-butyl peroxide anions are obtained using slow electron velocity-map imaging. The spectra show highly structured bands corresponding to detachment to the X∼A″ and A∼A electronic states of the neutral radical and represent a notable improvement in resolution over previous photoelectron spectra. We report an electron affinity of 1.

A complementary palette of NanoCluster Beacons.

NanoCluster Beacons (NCBs), which use few-atom DNA-templated silver clusters as reporters, are a type of activatable molecular probes that are low-cost and easy to prepare. While NCBs provide a high fluorescence enhancement ratio upon activation, their activation colors are currently limited. Here we report a simple method to design NCBs with complementary emission colors, creating a set of multicolor probes for homogeneous, separation-free detection.

DNA/RNA Detection Using DNA-Templated Few-Atom Silver Nanoclusters.

DNA-templated few-atom silver nanoclusters (DNA/Ag NCs) are a new class of organic/inorganic composite nanomaterials whose fluorescence emission can be tuned throughout the visible and near-IR range by simply programming the template sequences. Compared to organic dyes, DNA/Ag NCs can be brighter and more photostable. Compared to quantum dots, DNA/Ag NCs are smaller, less prone to blinking on long timescales, and do not have a toxic core.