998 resultados para ORIENTATION RELAXATION


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The S0 → S1 vibronic spectrum and S1 state nonradiative relaxation of jet-cooled keto-amino 5-fluorocytosine (5FCyt) are investigated by two-color resonant two-photon ionization spectroscopy at 0.3 and 0.05 cm–1 resolution. The 000 rotational band contour is polarized in-plane, implying that the electronic transition is 1ππ*. The electronic transition dipole moment orientation and the changes of rotational constants agree closely with the SCS-CC2 calculated values for the 1ππ* (S1) transition of 5FCyt. The spectral region from 0 to 300 cm–1 is dominated by overtone and combination bands of the out-of-plane ν1′ (boat), ν2′ (butterfly), and ν3′ (HN–C6H twist) vibrations, implying that the pyrimidinone frame is distorted out-of-plane by the 1ππ* excitation, in agreement with SCS-CC2 calculations. The number of vibronic bands rises strongly around +350 cm–1; this is attributed to the 1ππ* state barrier to planarity that corresponds to the central maximum of the double-minimum out-of-plane vibrational potentials along the ν1′, ν2′, and ν3′ coordinates, which gives rise to a high density of vibronic excitations. At +1200 cm–1, rapid nonradiative relaxation (knr ≥ 1012 s–1) sets in, which we interpret as the height of the 1ππ* state barrier in front of the lowest S1/S0 conical intersection. This barrier in 5FCyt is 3 times higher than that in cytosine. The lifetimes of the ν′ = 0, 2ν1′, 2ν2′, 2ν1′ + 2ν2′, 4ν2′, and 2ν1′ + 4ν2′ levels are determined from Lorentzian widths fitted to the rotational band contours and are τ ≥ 75 ps for ν′ = 0, decreasing to τ ≥ 55 ps at the 2ν1′ + 4ν2′ level at +234 cm–1. These gas-phase lifetimes are twice those of S1 state cytosine and 10–100 times those of the other canonical nucleobases in the gas phase. On the other hand, the 5FCyt gas-phase lifetime is close to the 73 ps lifetime in room-temperature solvents. This lack of dependence on temperature and on the surrounding medium implies that the 5FCyt nonradiative relaxation from its S1 (1ππ*) state is essentially controlled by the same ∼1200 cm–1 barrier and conical intersection both in the gas phase and in solution.

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A new bridge technique for the measurement of the dielectric absorption of liquids and solutions at microwave frequencies has been described and its accuracy assessed. 'l'he dielectric data of the systems studied is discussed in terms of the relaxation processes contributing to the dielectric absorption and the apparent dipole moments. Pyridine, thiophen and furan in solution have a distribution of relaxation times which may be attributed to the small size of the solute molecules relative to the solvent. Larger rigid molecules in solution were characterized by a single relaxation time as would be anticipated from theory. The dielectric data of toluene, ethyl-, isopropyl- and t-butylbenzene as pure liquids and in solution were described by two relaxation times, one identified with molecular re-orientation and a shorter relaxation time.· The subsequent work was investigation of the possible explanations of this short relaxation process. Comparable short relaxation times were obtained from the analysis of the dielectric data of solutions of p-chloro- and p-bromotoluene below 40°C, o- and m-xylene at 25°C and 1-methyl- and 2 methylnaphthalene at 50 C. Rigid molecules of similar shapes and sizes were characterized by a single relaxation time identified with molecular re-orientation. Contributions from a long relaxation process attributed to dipolar origins were reported for solutions of nitrobenzene, benzonitrile and p-nitrotoluene. A short relaxation process of possible dipolar origins contributed to the dielectric absorption of 4-methyl- and 4-t-butylpyridine in cyclohexane at 25°C. It was concluded that the most plausible explanation of the short relaxation process of the alkyl-aryl hydrocarbons studied appears to be intramolecular relaxation about the alkyl-aryl bond. Finally the mean relaxation times of some phenylsubstituted compounds were investigated to evaluate any shortening due to contributions from the process of relaxation about the phenyl-central atom bond. The relaxation times of triphenylsilane and phenyltrimethylsilane were significantly short.

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The impact of service direction, service training and staff behaviours on perceptions of service delivery are examined. The impact of managerial behaviour in the form of internal market orientation (IMO) on the attitudes of frontline staff towards the firm and its consequent influence on their customer oriented behaviours is also examined. Frontline service staff working in the consumer transport industry were surveyed to provide subjective data about the constructs of interest in this study, and the data were analysed using structural equations modelling employing partial least squares estimation. The data indicate significant relationships between internal market orientation (IMO), the attitudes of the employees to the firm and their consequent behaviour towards customers. Customer orientation, service direction and service training are all identified as antecedents to high levels of service delivery. The study contributes to marketing theory by providing quantitative evidence to support assumptions that internal marketing has an impact on services success. For marketing practitioners, the research findings offer additional information about the management, training and motivation of service staff towards service excellence.

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This paper examines the impact of service orientation (SO) on relationship quality, and its consequences for consumer behaviour in the travel industry. Specifically consumers' positive behavioural intentions, perceptions of switching costs, and consumer activism are examined as consequences of relationship quality (RQ). A sample of leisure and business travellers on a cross sea ferry were surveyed using a consumer intercept methodology. We find that SO has a significant and positive impact on RQ and that RQ has a positive impact on positive behavioural intentions and perceptions of switching costs. Both RQ and switching costs were found to reduce consumer activism. The implications of these findings for service managers and academics are discussed and directions forfuture research presented.

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Partially aligned and oriented polyacrylonitrile(PAN)-based nanofibers were electrospun from PAN and SWNTs/PAN in the solution of dimethylformamide(DMF) to make the carbon nanofibers. The as-spun nanofibers were hot-stretched in an oven to enhance its orientation and crystallinity. Then it were stabilized at 250 square under a stretched stress, and carbonized at 1000 square in N-2 atmosphere by fixing the length of the stabilized nanofiber to convert them into carbon nanofibers. With this hot-stretched process and with the introduction of SWNTs, the mechanical properties will be enhanced correspondingly. The crystallinity of the stretched fibers confirmed by X-ray diffraction has also increased. For PAN nanofibers, the improved fiber alignment and crystallinity resulted in the increased mechanical properties, such as the modulus and tensile strength of the nanofibers. It was concluded that the hot-stretched nanofiber and the SWNTs/PAN nanofibers can be used as a potential precursor to produce high-performance carbon composites.

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Reflecting its importance to thc financial success of organisations, interest in consumer loyalty continues unabated. However, there are still many unanswered questions about its conceptualisation and measurement.These questions must he resolved before academics and practitioners can usefully apply the concept. We argue that consumer loyalty is best conceptualised as a multi-dimensional phenomenon. Based on this multi-dimensional view, we develop and test a new measure of consumer loyalty. We hypothesise a threedimensional structure containing affective, temporal and instrumental dimensions, Results from a preliminary test are reported. The results indicate that the construct can be reprcxeuted with two dimensions: affective and temporal loyally. As an additional check on the reliability of our results, we find significant correlations between these two dimensions and a measure of behavioural loyalty.

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This paper reports on the performance of 58 11 to 12-year-olds on a spatial visualization task and a spatial orientation task. The students completed these tasks and explained their thinking during individual interviews. The qualitative data were analysed to inform pedagogical content knowledge for spatial activities. The study revealed that “matching” or “matching and eliminating” were the typical strategies that students employed on these spatial tasks. However, errors in making associations between parts of the same or different shapes were noted. Students also experienced general difficulties with visual memory and language use to explain their thinking. The students’ specific difficulties in spatial visualization related to obscured items, the perspective used, and the placement and orientation of shapes.

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This study investigated the longitudinal performance of 378 students who completed mathematics items rich in graphics. Specifically, this study explored student performance across axis (e.g., numbers lines), opposed-position (e.g., line and column graphs) and circular (e.g., pie charts) items over a three-year period (ages 9-11 years). The results of the study revealed significant performance differences in the favour of boys on graphics items that were represented in horizontal and vertical displays. There were no gender differences on items that were represented in a circular manner.

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Internal marketing has been discussed in the management and academic literature for over three decades, yet it remains ill defined and poorly operationalized. This paper responds to calls for research to develop a single clear understanding of the construct, for the development of a suitable instrument to measure it, and for empirical evidence of its impact. Existing, divergent conceptualization of internal marketing are explored, and a new, multidimensional construct, describing the managerial behaviors associated with internal marketing is developed, and termed internal market orientation (IMO). IMO represents the adaptation of market orientation to the context of employer-employee exchanges in the internal market. The paper describes the development of a valid and reliable measure of IMO in a retail services context. Five dimensions of IMO are identified and confirmed. These are 1) formal written information generation, 2) formal face-to-face information generation, 3) informal information generation, 4) communication and dissemination of information, and 5) responding to this internal market information. The impact of IMO on important organizational factors is also explored. Results indicate positive consequences for customer satisfaction, relative competitive position, staff attitudes, staff retention and staff compliance.