On the rearrangement and dissociation mechanism of SiH4+ in its triply-degenerate ground state.

An ab initio molecular orbital study has been performed to explore the structural rearrangement and dissociation of SiH4+ radical cation at the X̃2T2 ground electronic state. All stationary points located on the lowest adiabatic sheet of Jahn-Teller (JT) split X̃2T2 state are fully optimized and characterized by performing harmonic vibrational frequency calculations. The structural rearrangement is predicted to start with JT distortions involving the doubly-degenerate (e) and triply-degenerate (t2) modes. The e mode reduces the initial Td symmetry of the SiH4+ ground state to a D2d saddle point, which eventually dissociates into the SiH3+(2A1) + H products via C3v local minimum. In turn, an e-type bending of αH-Si-H yields the SiH2+(2A1) + H2 products through the first C3v local minimum and then the Cs(2A') global minimum. In the alternative pathway, the t2 mode distorts the initial Td symmetry into a loosely bound C3v local minimum, which further dissociates into the SiH3+(2A1) + H asymptote via totally symmetric Si-H stretching mode, and SiH2+(2A1) + H2 products via H-Si-H bending (e) mode through the Cs(2A') global minimum. It is further predicted that the Cs global minimum interconverts equivalent structures via a C2v transition structure. In addition, the two dissociation products are found to be connected by a second C2v transition structure.

Vibronic coupling and ultrafast relaxation dynamics in the first five excited singlet electronic states of bithiophene.

The vibronic structure and nuclear dynamics in the first five excited singlet electronic states of bithiophene (2T) are investigated here. Specifically, considerations are given to comprehend the first two structureless and broad electronic absorption bands and the role of nonadiabatic coupling in the excited state relaxation mechanism of 2T in the gas phase. Associated potential energy surfaces (PESs) are established by constructing a model vibronic coupling Hamiltonian using 18 vibrational degrees of freedom and extensive ab initio electronic structure calculations. The topographies of these PESs are critically examined, and multiple conical intersections are established. The nuclear dynamics calculations are performed by propagating wave packets on the coupled electronic manifold. The present theoretical results are in good agreement with the experimental observations. It is found that strong nonadiabatic coupling between the S1-S4 and S1-S5 states along totally symmetric modes is predominantly responsible for the structureless and broad first absorption band, and overlapping S2, S3, S4, and S5 states form the second absorption band. Photorelaxation from the highly excited S5 to the lowest S1 state takes place through a cascade of diabatic population transfers among the S1-S4-S5 electronic manifold within the first ∼100 fs. Totally symmetric C=C stretching, C-S stretching, C-H wagging, ring puckering, and inter-ring bending modes collectively drive such relaxation dynamics.

Design, Synthesis and In-Silico Studies of Piperidine-Dihydropyridine Hybrids as Anticancer Agents.

In this study, we designed, synthesized and characterized a novel series of piperidine-dihydropyridine hybrid compounds and characterized them by 1H-NMR, 13C NMR, mass spectrometry (MS), and elemental analysis. Subsequently, we assessed their in vitro anticancer potentials against the human breast adenocarcinoma cell line MCF-7 and the lung cancer cell line A-549. Several of these compounds demonstrated significant activity, with IC50 values ranging from 15.94 µM to 48.04 µM for A-549 and 24.68 µM to 59.12 µM for MCF-7, when compared to the reference drug Cisplatin.Notably, a compound featuring a 3-fluoro substitution in the carboxamide series exhibited robust inhibitory effects, with an IC50 of 15.94±0.201 µM against A-549 cells and an IC50 of 22.12±0.213 µM against MCF-7 cells, respectively. Additionally, a compound containing a cyclobutyl ring displayed potent activity, with an IC50 of 16.56±0.125 µM against A-549 and an IC50 of 24.68±0.217 µM against MCF-7 cells, respectively. Furthermore, molecular docking studies against the Epidermal Growth Factor Receptor (EGFR) (PDB ID: 2J6M) revealed favourable binding scores and interactions, suggesting their potential as promising candidates for further investigation in the context of anticancer drug development.

Parents of Very Young Children with Congenital Heart Defects Report Good Quality of Life for Their Children and Families Regardless of Defect Severity.

The purpose of this study was to investigate parent reports of quality of life for their very young children with congenital heart defects (CHD) and to compare their scores to previously published data. Parents of children 1-3 years old with CHD or innocent heart murmurs completed the Pediatric Quality of Life Inventory (PedsQL) core, cardiac, and family impact modules. Multivariable regression analyses assessed the impact of age, sex, family income, and CHD treatment history (study group) on PedsQL scores. Correlations between family impact and core/cardiac modules were examined. PedsQL scores were compared to healthy norms. 140 parents of young children participated within four study groups: CHD no treatment (n = 44), CHD treatment without bypass (n = 26), CHD treatment with bypass (n = 42) ,and innocent heart murmurs (n = 28). Male sex was associated with higher core (F = 4.16, p = 0.04, σ2 = .03) and cardiac quality of life (F = 4.41, p = .04, σ2 = 0.04). Higher family income was associated with higher family quality of life (F = 8.89, p < .01, σ2 = 0.13). Parents of children with innocent heart murmurs and children with CHD not requiring treatment had higher core quality of life compared to young healthy children. Cardiac-related quality of life scores were associated with family impact (r = 0.68) and core module (r = 0.63) quality of life scores. Parents of very young children with CHD report good quality of life for their children and families. Quality of life exceeds in children with innocent murmurs or CHD not requiring repair. Parents report a lower quality of life among girls, and lower family quality of life is associated with lower family income.

Status and Prospects of Next Generation Sequencing Technologies in Crop Plants.

The history of DNA sequencing dates back to 1970s. During this period the two first generation nucleotide sequencing techniques were developed. Subsequently the Sanger's dideoxy method of sequencing gained popularity over Maxam and Gilbert's chemical method of sequencing. However, in the last decade, we have observed revolutionary changes in DNA sequencing technologies leading to the emergence of next-generation sequencing (NGS) techniques. NGS technologies have enhanced the throughput and speed of sequencing combined with bringing down the overall cost of the process over a time. The major applications of NGS technologies being genome sequencing and resequencing, transcriptomics, metagenomics in relation to plant-microbe interactions, exon and genome capturing, development of molecular markers and evolutionary studies. In this review, we present a broader picture of evolution of NGS tools, its various applications in crop plants, and future prospects of the technology for crop improvement.

On the higher-order T2 ⊗ (e + t2) Jahn-Teller coupling effects in the photodetachment spectrum of the alanate anion (AlH4-).

The static and dynamic aspects of the T2 ⊗ (e + t2) Jahn-Teller coupling effects in the X[combining tilde]2T2 electronic state of the AlH4 radical are investigated theoretically by probing the first photodetachment spectrum of AlH4-. Associated potential energy surfaces up to two-dimensional space of nuclear coordinates are established from extensive electronic structure calculations and nuclear dynamics calculations are done on them via wave packet propagation including the nonadiabatic coupling of the three electronic sheets. The theoretical results are in good agreement with experimental observations. The present study established that the higher-order JT coupling terms (beyond the second order terms, which is considered to be standard JT theory) are important to correctly reproduce the spectral intensity and diffused vibrational structure of the X[combining tilde]2T2 electronic state of AlH4. More specifically, we found that expansions of the JT coupling parameters up to the fourth order of the nuclear coordinates are necessary for a reliable description of the JT effect in this electronic manifold. Various static aspects of the JT coupling effects and vibrational progressions under the complex and highly irregular X[combining tilde]2T2 vibronic band of the AlH4 radical are examined in detail.

Origin of distinct structural symmetry of the neopentane cation in the ground electronic state compared to the methane cation.

An ab initio quantum dynamics study has been performed to explore the distinct structural symmetry of C(CH3)4(+) in the ground electronic state compared to CH4(+). Additionally, the underlying details of the highly diffuse and complex vibronic structure of the first photoelectron band of C(CH3)4 have been investigated. Associated potential energy surfaces over the two-dimensional space of nuclear coordinates, subject to the T2⊗ (e + t2) Jahn-Teller effect, are established from extensive electronic structure calculations and (then) the nuclear dynamics calculations are done on them via wave packet propagation including the nonadiabatic coupling of the three electronic sheets. The theoretical results are in good agreement with experimental observations. The JT stabilization energies due to T2⊗e, T2⊗t2 and T2⊗ (e + t2) distortions in the X[combining tilde](2)T2 electronic manifold of C(CH3)4(+) illustrate that the highest stabilization occurs through the T2⊗t2-JT distortion (in the ground state of C(CH3)4(+)). However, CH4(+) gains such maximum stabilization due to T2⊗ (e + t2)-JT distortion. From this novel result and applying the epikernel principle, we propose that the structural evolution of C(CH3)4(+) from Td to C3v minimum energy configuration occurs via JT active vibrations of t2 symmetry, whereas CH4(+) rearranges to the C2v structure through a combination of JT active e and t2 bending vibrations.

Structural evolution of the methane cation in subfemtosecond photodynamics.

An ab initio quantum dynamics study has been performed to explore the structural rearrangement of ground state CH4 (+) in subfemtosecond resolved photodynamics. The method utilizes time-dependent wave-packet propagation on the X˜(2)T2 electronic manifold of the title cation in full dimensionality, including nonadiabatic coupling of the three electronic sheets. Good agreement is obtained with recent experiments [Baker et al., Science 312, 424 (2006)] which use high-order harmonic generation to probe the attosecond proton dynamics. The novel results provide direct theoretical support of the observations while unravelling the underlying details. With the geometrical changes obtained by calculating the expectation values of the nuclear coordinates as a function of time, the structural evolution is predicted to begin through activation of the totally symmetric a1 and doubly degenerate e modes. While the former retains the original Td symmetry of the cation, the Jahn-Teller active e mode conducts it to a D2d structure. At ∼1.85 fs, the intermediate D2d structure is further predicted to rearrange to local C2v minimum geometry via Jahn-Teller active bending vibrations of t2 symmetry.

Development and validation of a generic scale for use in transition programmes to measure self-management skills in adolescents with chronic health conditions: the TRANSITION-Q.

AIM: To develop a generic self-management skills scale for use with adolescents diagnosed with a chronic health condition who are aged 12 to 18 years. BACKGROUND: There is a lack of methodologically sound scales for healthcare teams to use to measure self-management skills in adolescents with chronic conditions transitioning to adult care. METHODS: Adolescents aged 12 to 18 years with a broad range of chronic health conditions, including neurodevelopmental conditions, were recruited from May to August 2013 from nine outpatient clinics at McMaster Children's Hospital (Canada). Thirty-two participated in a cognitive interview, and 337 completed a questionnaire booklet. Interviews were used to develop the TRANSITION-Q. Rasch measurement theory (RMT) analysis was used to identify items that represent the best indicators of self-management skills. Traditional psychometric tests of measurement performance were also conducted. RESULTS: The response rate was 92% (32/32 cognitive; 337/371 field test). RMT analysis resulted in a 14-item scale with three response options. The overall fit of the observed data to that expected by the Rasch model was non-significant, providing support that this new scale measured a unidimensional construct. Other tests supported the scale as scientifically sound, e.g. Person Separation Index = 0.82; good item fit statistics; no differential item function by age or gender; low residual correlations between items; Cronbach's alpha = 0.85; test-retest reliability = 0.90; and tests of construct validity that showed, as hypothesized, fewer skills in younger participants and in participants who required assistance to complete the scale. Finally, participants who agreed they are ready to transfer to adult healthcare reported higher TRANSITION-Q scores than did participants who disagreed. CONCLUSIONS: The TRANSITION-Q is a short, clinically meaningful and psychometrically sound scale. This generic scale can be used in research and in paediatric and adolescent clinics to help evaluate readiness for transition.

Silane radical cation: a theoretical account on the Jahn-Teller effect at a triple degeneracy.

An ab initio quantum dynamics study is performed to examine the complex nuclear motion underlying the first photoelectron band of the silane molecule due to Jahn-Teller distortion via T2⊗(e+t2+t2) coupling. The problem is investigated by employing a quadratic vibronic coupling model for the Hamiltonian. All sheets of the required potential energy surface are established through extensive electronic structure calculations using the multireference configuration-interaction method. They cover at most two dimensions of the full 9D coordinate space, with the parameters defining the model Hamiltonian being determined by a least-squares fitting procedure. The results are compared with the available experimental data and discussed in relation to those obtained for the methane radical cation. The quadratic couplings of Jahn-Teller active vibrational modes are found to have a crucial role on the irregular vibronic structure, intensity of the spectral excitations, and overall width of the first photoelectron band of the title molecule. The impact of large amplitude motions on the vibronic structure and dynamics of the first photoelectron band has also been examined by varying their linear coupling parameters up to ±10%.

Occurrence of canine parvovirus type 2c in diarrhoeic faeces of dogs in Kolkata, India.

Canine parvovirus-2(CPV-2) causes a highly contagious disease of dogs characterised by acute hemorrhagic gastroenteritis, lethargy, vomiting, fever and usually bloody or mucoid diarrhoea. In the present study, 41 faecal samples collected from dogs exhibiting the signs of fever, vomition, bloody or mucoid diarrhoea in Kolkata, India were screened by haemagglutination test and PCR for detection of capsid protein coding VP2 gene. The viral genotype was detected by multiplex PCR and analysis of partial VP2 gene nucleotide sequences of selected PCR products with bioinformatics tool. Thirteen (31.71%) samples were found positive with HA titre ≥ 32 whereas 28 (68.29%) samples were positive by PCR of VP2 gene indicating higher sensitivity of PCR. Highest occurrence of CPV-2 was observed in the age group of 1-6 months (80.65%) and non-descript breeds with no history of vaccination (85%). Three samples were antigenic type CPV-2a, rest were CPV-2b/CPV 2c. Six CPV sequences were found to be highly similar to published CPV 2c sequences in BLAST analysis revealing a maximum identity of 99-100% with other CPV-2c strains and clustered together with CPV-2c strains of India and other countries in phylogenetic analysis. The present study highlights the need for continuous monitoring of samples to detect gradual changes in circulating CPV-2 genotypes in India.

Quadratic coupling treatment of the Jahn-Teller effect in the triply-degenerate electronic state of CH4(+): can one account for floppiness?

The Jahn-Teller (JT) coupling effects in the triply degenerate ground electronic state of methane radical cation are investigated theoretically within a quadratic vibronic coupling approach. The underlying potential energy surfaces over the two-dimensional space of nuclear coordinates, subject to the T(2) ⊗ (e + t(2) + t(2)) Jahn-Teller effect, are established from extensive ab initio calculations using the multi-reference configuration interaction method and then employed to determine the various parameters of a diabatic Hamiltonian of this system. Our previous investigation [T. Mondal and A. J. C. Varandas, J. Chem. Phys. 135, 174304 (2011)], relying on the linear vibronic coupling approach augmented by only a diagonal second-order term of the totally symmetric mode, are extended here by including all possible quadratic coupling constants of JT active e and t(2) modes. Inclusion of these quadratic couplings is found to be important to reproduce correctly the broad vibrational structure and for a better description of dynamical JT effect in the first vibronic band of this radical cation. The impact of large amplitude motions (which are responsible for floppiness of the molecule) on the vibronic structure and dynamics of the first photoelectron band have been examined via readjustment of their linear coupling parameters up to ±10%.

Photophysics of fluorinated benzene. III. Hexafluorobenzene.

A theoretical study of the photoabsorption spectroscopy of hexafluorobenzene (HFBz) is presented in this paper. The chemical effect due to fluorine atom substitution on the electronic structure of benzene (Bz) saturates in HFBz. State- of-the-art quantum chemistry calculations are carried out to establish potential energy surfaces and coupling surfaces of five energetically low-lying electronic (two of them are orbitally degenerate) states of HFBz. Coupling of these electronic states caused by the Jahn-Teller (JT) and pseudo-Jahn-Teller (PJT) type of interactions are examined. The impact of these couplings on the nuclear dynamics of the participating electronic states is thoroughly investigated by quantum mechanical methods and the results are compared with those observed in the experiments. The complex structure of the S(1) ← S(0) absorption band is found to originate from a very strong nonadiabatic coupling of the S(2) (of πσ* origin) and S(1) (of ππ* origin) state. While S(2) state is orbitally degenerate and JT active, the S(1) state is nondegenerate. These states form energetically low-lying conical intersections (CIs) in HFBz. These CIs are found to be the mechanistic bottleneck of the observed low quantum yield of fluorescence emission, non overlapping absorption, and emission bands of HFBz and contribute to the spectral width. Justification is also provided for the observed two peaks in the second absorption (the unassigned "c band") band of HFBz. The peaks observed in the third, fourth, and fifth absorption bands are also identified and assigned.

The Jahn-Teller effect in the triply degenerate electronic state of methane radical cation.

A quantum dynamics study is performed to examine the complex nuclear motion underlying the first photoelectron band of methane. The broad and highly overlapping structures of the latter are found to originate from transitions to the ground electronic state, X(2)T(2), of the methane radical cation. Ab initio calculations have also been carried out to establish the potential energy surfaces for the triply degenerate electronic manifold of CH(4)(+). A suitable diabatic vibronic Hamiltonian has been devised and the nonadiabatic effects due to Jahn-Teller conical intersections on the vibronic dynamics investigated in detail. The theoretical results show fair accord with experiment.

Photophysics of fluorinated benzene. I. Quantum chemistry.

The electronic structure of energetically low-lying excited singlet states of fluorobenzene molecules is investigated here. Increasing fluorine substitution alters the nature of the excited electronic states and the so-called perfluoro effect is observed for penta- and hexafluorobenzene. Detailed quantum chemistry calculations are carried out at the equation-of-motion coupled-cluster singles and doubles level of theory to establish the potential energy surfaces of the low-lying electronic states of mono-, di- (ortho- and meta-), and pentafluorobenzene molecules. A sequence of low-energy conical intersections among the electronic potential energy surfaces is established. It is found that increasing fluorine substitution lowers the energy of the pisigma* electronic state and leads to conical intersections between the S(1) and S(2) electronic states of pentafluorobenzene. Existence of numerous conical intersections among the excited electronic states of these molecules forms the mechanistic details underlying their nonradiative internal conversion. In particular, the slow and biexponential fluorescence emission in pentafluorobenzene is attributed to the existence of low-lying S(1)-S(2) conical intersections. The electronic structure data are analyzed in detail and the coupling mechanism among various electronic excited states of mono-, di-, and pentafluorobenzene molecules is established.

Photophysics of fluorinated benzene. II. Quantum dynamics.

Nuclear dynamics in the coupled electronic states of mono-, di-(ortho and meta), and pentafluorobenzene molecules is investigated here. Attempts are specifically made to understand the complexity and broadening of the recorded gas phase electronic absorption spectra of these molecules. Justification is also provided for the low quantum yield of fluorescence emission with increasing number of fluorine substitutions. The nuclear dynamics is simulated from first principles both by time-independent and time-dependent quantum mechanical methods. Potential energy surfaces of the low-lying excited electronic states of these molecules constructed in Paper I [Mondal and Mahapatra, J. Chem. Phys. 133, 084304 (2010)] are employed for the purpose. Theoretical results presented in this paper are compared with the available experimental data and the agreement between the two is found to be excellent. While structured electronic absorption bands are observed for the S(1) state of mono- and difluorobenzene molecules, the same for the pentafluorobenzene is broad and structureless. Occurrence of S(1)-S(2) conical intersections in pentafluorobenzene leads to a nonradiative internal conversion of the S(1) state in approximately 165 fs and contributes to the broadening of the S(1)<--S(0) absorption band and a biexponential decay of its fluorescence emission.

Assessing the clinical significance of echocardiograms in determining treatment of patent ductus arteriosus in neonates.

BACKGROUND: To evaluate the utility of echocardiogram (ECHO) in detection and treatment of patent ductus arteriosus (PDA) and hemodynamically significant PDA (hsPDA) in preterm neonates. METHODS: This was a retrospective case-control study of all preterm infants born or admitted to the level III Neonatal Intensive Care Unit in McMaster Children's Hospital from January 2009 to January 2013. These cases were further classified into the following sub-groups: group A) hsPDA confirmed on ECHO; and the control, group B) PDA (but not hemodynamically significant) confirmed on ECHO. Patients without an ECHO were excluded from all analyses. The primary outcome was incidence of treatment for PDA. RESULTS: PDA treatment was administered in 83.3% and 11.2% of patients in groups A and B respectively (P < 0.05). Among patients with a hsPDA within group A, 17% did not receive treatment, while 11% of patients with non-hemodynamically significant PDA received treatment for the PDA. Within the cohort of patients who received treatment for a hsPDA, gestational age below 35 weeks as well as murmurs heard on auscultation were both found to be predictors of treatment. CONCLUSION: While the ECHO remains the gold standard for detecting pathological PDA, there is evidence that other traditional clinical measures continue to guide clinical practice and treatment decisions. Further research is required to gain an understanding of how clinical measures and ECHO may be used in conjunction to optimize resource utilization.

trans-Dichloro-bis-(arylazoimidazole)palladium(II): synthesis, structure, photoisomerization, and DFT calculation.

Reaction between PdCl(2) and 1-alkyl-2-(arylazo)imidazole (RaaiR') or 1-alkyl-2-(naphthyl-alpha/beta-azo)imidazole (alpha/beta-NaiR') under reflux in ethanol has isolated complexes of compositions Pd(RaaiR')(2)Cl(2) (5, 6) and Pd(alpha/beta-NaiR')(2)Cl(2) (7, 8). The X-ray structure determination of one of the molecules, Pd(alpha-NaiBz)(2)Cl(2) (7c), has reported a trans-PdCl(2) configuration, and alpha-NaiBz acts as monodentate N(imidazole) donor ligand. The spectral (IR, UV-vis, (1)H NMR) data support the structure. UV light irradiation (light source: Perkin-Elmer LS 55 spectrofluorimeter, Xenon discharge lamp, lambda = 360-396 nm) in a MeCN solution of the complexes shows E-to-Z isomerization of the coordinated azoimidazole unit. The reverse transformation, Z-to-E, is very slow with visible light irradiation. Quantum yields (phi(E-->Z)) of E-to-Z isomerization are calculated, and phi is lower than that of the free ligand but comparable with those of Cd(II) and Hg(II) complexes of the same ligand. The Z-to-E isomerization is a thermally induced process. The activation energy (E(a)) of Z-to-E isomerization is calculated by controlled-temperature experimentation. cis-Pd(azoimidazole)Cl(2) complexes (azomidazole acts as N(imidazole) and N(azo) chelating ligand) do not respond upon light irradiation, which supports the idea that the presence of noncoordinated azo-N to make free azo (-N=N-) function is important to reveal photochromic activity. DFT calculation of Pd(alpha-NaiBz)(2)Cl(2) (7c) has suggested that the HOMO of the molecule is constituted of Pd (32%) and Cl (66%), and hence photo excitation may use the energy of Pd and Cl instead of that of the photofunctional -N=N-Ar motif; thus, the rate of photoisomerization and quantum yield decrease versus the free ligand values.

The Jahn-Teller and pseudo-Jahn-Teller effects in the low-lying electronic states of 1,3,5-trifluorobenzene radical cation.

Static and dynamic aspects of the multimode Jahn-Teller (JT) and pseudo-Jahn-Teller (PJT) interactions in the low-lying electronic states of 1,3,5-trifluorobenzene radical cation (TFBZ(+)) are investigated by an ab initio quantum dynamical approach. The electronic ground state (tilde X(2)E'') of TFBZ(+) is energetically well separated from its excited states. The first three excited electronic states (tilde A(2)A(2)", tilde B(2)E' and tilde C(2)A(2)') are however, energetically close. A sequence of low-energy conical intersections underlying the JT and PJT interactions among these electronic states is established. Nonadiabatic effects due to these intersections on the vibronic dynamics are examined in detail. The theoretical results are compared with the low resolution and also better resolved experimental data. The impact of increasing fluorination on the structure and dynamics of the excited states is discussed in relation to the parent benzene radical cation and its mono- and di-fluoro derivatives.

Complex dynamics at conical intersections: vibronic spectra and ultrafast decay of electronically excited trifluoroacetonitrile radical cation.

An ab initio quantum dynamical study is performed here to examine the complex nuclear motion underlying the first two photoelectron bands of trifluoroacetonitrile. The highly overlapping structures of the latter are found to originate from transitions to the five lowest electronic states (viz., X(2)E, A(2)A1, B(2)A2, C(2)A1, and D(2)E) of the trifluoroacetonitrile radical cation. The Jahn-Teller (JT) instability of the doubly degenerate X and, D and their pseudo-Jahn-Teller (PJT) interactions with the nondegenerate A, B, and C electronic states along the degenerate vibrational modes lead to multiple multidimensional conical intersections and complex nuclear trajectories through them. It is found that the JT splitting is very weak in the X and relatively stronger in the D state. However, the PJT couplings play the pivotal role in the detailed shape of the vibronic bands of the radical cation. Ultrafast nonradiative decay of electronically excited radical cation has been examined. The findings of this paper are compared with the experimental data and are also discussed in relation to those observed for the methyl cyanide radical cation.