A primary elimination channel of the chlorine molecule in the one-photon dissociation of SOCl2 at 248 nm was investigated using cavity ring-down absorption spectroscopy (CRDS). By means of spectral simulation, the ratio of the vibrational population in the v = 0, 1, and 2 levels was evaluated to be 1:(0.10 ± 0.02):(0.009 ± 0.005), corresponding to a Boltzmann vibrational temperature of 340 ± 30 K. The Cl2 molecular channel was obtained with a quantum yield of 0.4 ± 0.2 from the X1A′ ground state of SOCl2via internal conversion. The dissociation mechanism differs from a prior study where a smaller yield of <3% was obtained, initiated from the 21A′ excited state. Temperature-dependence measurements of the Cl2 fragment turn out to support our mechanism. With the aid of ab initio potential energy calculations, two dissociation routes to the molecular products were found, including one synchronous dissociation pathway via a three-center transition state (TS) and the other sequential dissociation pathway via a roaming-mediated isomerization TS. The latter mechanism with a lower energy barrier dominates the dissociation reaction. This journal is © the Owner Societies.

Investigations were carried out on the carbon-dots (C-dots) based fluorescent off - on (Fe 3 €‰+ €‰ - S 2 O 3 2 ') and on - off (Zn 2 €‰+ €‰ - PO 4 3 ') sensors for the detection of metal ions and anions. The sensor system exhibits excellent selectivity and sensitivity towards the detection of biologically important Fe 3 €‰+ €‰, Zn 2 €‰+ €‰ metal ions and S 2 O 3 2 ', PO 4 3 ' anions. It was found that the functional group on the C-dots surface plays crucial role in metal ions and anions detection. Inspired by the sensing results, we demonstrate C-dots based molecular logic gates operation using metal ions and anions as the chemical input. Herein, YES, NOT, OR, XOR and IMPLICATION (IMP) logic gates were constructed based on the selection of metal ions and anions as inputs. This carbon-dots sensor can be utilized as various logic gates at the molecular level and it will show better applicability for the next generation of molecular logic gates. Their promising properties of C-dots may open up a new paradigm for establishing the chemical logic gates via fluorescent chemosensors.

Following photodissociation of acetaldehyde (CH3CHO) at 308 nm, the CO(v = 1-4) fragment is acquired using time-resolved Fourier-transform infrared emission spectroscopy. The CO(v = 1) rotational distribution shows a bimodal feature; the low- and high-J components result from H-roaming around CH3CO core and CH3-roaming around CHO radical, respectively, in consistency with a recent assignment by Kable and co-workers (Lee et al., Chem. Sci. 5, 4633 (2014)). The H-roaming pathway disappears at the CO(v 2) states, because of insufficient available energy following bond-breaking of H + CH3CO. By analyzing the CH4 emission spectrum, we obtained a bimodal vibrational distribution; the low-energy component is ascribed to the transition state (TS) pathway, consistent with prediction by quasiclassical trajectory calculations, while the high-energy component results from H- and CH3-roamings. A branching fraction of H-roaming/CH3-roaming/TS contribution is evaluated to be (8% ± 3%)/(68% ± 10%)/(25% ± 5%), in which the TS pathway was observed for the first time. The three pathways proceed concomitantly along the electronic ground state surface. © 2015 AIP Publishing LLC.

Recent experimental and theoretical advances in the study of the dissociation of excited molecules are revealing unexpected mechanisms, when their outcomes are tackled by combining (i) space-time ion imaging of translational features, with (ii) spectroscopic probing of rotational and vibrational distributions; crucial is the assistance of (iii) the quantum chemistry of structural investigations of rearrangements of chemical bonds, and of (iv) the simulations of molecular dynamics to follow the evolution of selective bond stretching and breaking. Here we present results of such an integrated approach to methyl formate, HCOOCH3, the simplest of esters; the main focus is on the rotovibrationally excited CO (v = 1) product and in general on the energy distribution in the fragments. Previous laser studies of dissociation into CO and CH3OH at a sequence of various wavelengths discovered signatures of a roaming mechanism by the late arrival of CO (v = 0) products in time-of-flight ion imaging. Subsequent detailed investigations as a function of excitation energy provided the assessment of the threshold, which opens for triple breakdown into CO and further fragments H and CH3O, as spectroscopically characterized by ion imaging and FTIR respectively. Accompanying quantum mechanical electronic structure calculations and classical molecular dynamics simulations clarify the origin of these fragments through "roaming" pathways involving incipient radical intermediates at energies below the triple fragmentation threshold: a specific role is played by nonadiabatic transitions at a conical intersection between ground and excited states; alternative pathways focalize our attention to regions of the potential energy surfaces other than those in the neighbourhoods of saddle points along minimum energy paths: eventually this leads us to look for avenues in reaction kinetics beyond those of venerable transition state theories. This journal is © The Royal Society of Chemistry.

Carbon mesoporous materials (CPMs) have great potential in the field of heterogeneous catalysis. Highly dispersed ruthenium nanoparticles (RuNPs) embedded in three dimensional (3D) CPMs as catalysts with a high surface area (1474 m2 g-1) were prepared by microwave-thermal reduction processes. Characterization technologies including X-ray diffraction (XRD), N2 adsorption/desorption isotherm measurements, field emission transmission electron microscopy (FE-TEM), thermogravimetric analysis (TGA), hydrogen temperature-programmed reduction (H2-TPR), Raman spectroscopy and 13C solid state cross polarization and magic angle spinning (13C CP/MAS) NMR spectroscopy were utilized to scrutinize the catalysts. It was revealed that the Ru/CPM catalysts exhibited a highly ordered 3D mesoporous structure and a large surface area and were widely used as catalysts for reduction reactions. Reduction of p-nitroaniline (p-NA) and crystal violet (CV) using NaBH4 with the use of this catalyst was studied by means of UV-vis spectroscopy. Here, NaBH4 acts as a hydrogen donor. This catalyst shows an excellent catalytic activity towards reduction of p-NA and CV dye at room temperature. Due to the promising properties of CPMs, they can be utilized to fabricate 3D carbon-based materials for a variety of novel applications. © The Royal Society of Chemistry 2015.

A multi-center impulsive model has been recently developed to characterize the dynamic feature of product energy distribution in photodissociation of formaldehyde, H2CO → CO + H2. (J. Phys. Chem. A, 2015, 119, 29) The model is extended to predict the vector correlations among transition dipole moment μ of the parent molecule, recoil velocity v and rotational angular momentum j of the fragments produced via the transition state (TS) and roaming path. The correlation results of μ-j, j-j and μ-v vectors of the fragments are consistent with those reported using quasi-classical trajectory simulation on the global potential energy surface. In contrast to the TS route, the vector properties via the roaming path are loosely correlated. This work offers an alternative method to study stereodynamics of the photodissociation process, and is conducive to clarifying the origin of photofragment vector correlation especially for the roaming pathway. This journal is © the Owner Societies.