Rotational perturbations in the CN (B 2Σ+-X 2Σ+) tail band system. II. Identification of the CN (4Π) state and its vibrational levels

Experimental energy levels of 12C14N through marvel analysis

The cyano radical (CN) is a key molecule across many different factions of astronomy and chemistry. Accurate, empirical rovibronic energy levels with uncertainties are determined for eight doublet states of CN using the marvel (Measured Active Rotational-Vibrational Energy Levels) algorithm. 40 333 transitions were validated from 22 different published sources to generate 8083 spin-rovibronic energy levels. The empirical energy levels obtained from the marvel analysis are compared to current energy levels from the mollist line list. The mollist transition frequencies are updated with marvel energy level data which brings the frequencies obtained through experimental data up to 77.3 per cent from the original 11.3 per cent, with 92.6 per cent of the transitions with intensities over 10-23 cm molecule-1 at 1000 K now known from experimental data. At 2000 K, 100.0 per cent of the partition function is recovered using only marvel energy levels, while 98.2 per cent is still recovered at 5000 K.

Sticking probability of CN(X2Σ+) radicals onto amorphous carbon nitride films formed from the decomposition of BrCN induced by the microwave discharge flow of Ar

The sticking probability, s, of CN(X(2)Σ(+)) radicals onto amorphous carbon nitride (a-CN(x)) films with high [N]/([N]+[C]) ratios (≤0.5) was evaluated. CN(X(2)Σ(+)) radicals were generated from the decomposition of BrCN with the microwave discharge flow of Ar in the two experimental configurations, I and II, where the distance between the tip of the nozzle introducing BrCN is close (≈10 mm) to and distant (≈0.3 m) from the laser-beam path or the Si substrate, respectively. For each configuration, s was evaluated both under the desiccated and H(2)O-added conditions from the number density of CN(X(2)Σ(+)) evaluated from the intensity of the CN(A(2)Π(i)-X(2)Σ(+)) laser-induced fluorescence spectrum calibrated against Rayleigh scattering intensity of Ar, the flow speed measured by a time-resolved emission, and the film mass. The [N]/([N]+[C]) ratios of films were evaluated as 0.4-0.5 and 0.3 in the configurations I and II, respectively, from the compositional analysis using Rutherford back scattering and elastic recoil detection analysis together with the XPS analysis. The variation of s under various experimental conditions was discussed based on the electron densities in the reaction region and the relative density of the hydrogen-termination structures of the film surface.

Measurements of density and sticking probability of CN(X(2)Sigma(+)) radicals by laser-induced fluorescence spectroscopy

CN(X(2)Sigma(+)) radicals were produced by the decomposition of BrCN with the microwave discharge flow of Ar under the conditions of Ar pressure in the range of 0.40-0.70 Torr. The laser-induced fluorescence (LIF) spectra of the CN(A(2)Pi(i)-X(2)Sigma(+)), 4-0, 5-1, and 7-2 bands were observed, and their intensities were calibrated against Rayleigh-scattering intensity by Ar atoms, from which the CN(X(2)Sigma(+)) radical density (n(CN(X))) was determined as (0.67+/-0.25) x 10(18) to (4.42+/-0.83) x 10(18) m(-3). Hydrogenated amorphous carbon nitride (a-CN(x):H) films were formed by depositing the CN(X(2)Sigma(+)) radicals on Si substrates in the same reaction system as LIF. The sticking probability (s) of the CN(X(2)Sigma(+)) radicals onto the a-CN(x):H films was determined by using n(CN(X)), the flow speed, and the weight (w) of a-CN(x):H. The s value was determined as (6.4+/-6.4) x 10(-2) to (2.5+/-1.2) x 10(-2), where the errors are predominantly determined by those in n(CN(X)) and w. The procedure described in the present study will provide a methodology to determine the sticking probability of the precursor radicals of the film formation based on the gas-phase LIF spectroscopy.

Methylene: A Paradigm for Computational Quantum Chemistry

The year 1970 has been suggested as a starting date for the "third age of quantum chemistry," in which theory takes on not only qualitative but also quantitative value. In fact, each of the years 1960, 1970, 1972, and 1977 is of historical value in the unraveling of the structure and energetics of the CH(2) molecule, methylene. What took place for methylene, namely the establishment of credibility for theory, has subsequently taken place for many other molecules. Three important roles for quantitative theory are outlined: (i) theory precedes experiment; (ii) theory overturns experiment, as resolved by later experiments; and (iii) theory and experiment work together to gain insight that is afforded independently to neither. Several examples from each of the three classes are given.