排序方式: 共有51条查询结果,搜索用时 31 毫秒
11.
P. Stoppa D. De Vito S. Giorgianni A. Baldacci A. Gambi R. Wugt Larsen 《Molecular physics》2020,118(18)
The high-resolution infrared spectrum of CHD2 79Br has been investigated by Fourier transform spectroscopy in the range 540–615?cm?1 at an unapodised resolution of 0.0035?cm?1. This spectral region is characterised by the ν6 fundamental (584.8510?cm?1), corresponding to C–Br stretching mode, and its hot band 2ν6?ν6 (578.4333?cm?1). The spectral analysis resulted in the identification of 3430 transitions (J’?≤?73 and K'a ?≤?18) for the ν6 fundamental and 1212 transitions (J’?≤?49 and K'a ?≤?11) for the hot band 2ν6?ν6. The assigned data have been fitted using the Watson’s S-reduced Hamiltonian in the Ir representation and new constants for the ground state from about 24,600 combination differences and sets of parameters for the v 6?=?1 and 2 vibrational states have been obtained. From spectral simulations the intensity ratio between 2ν6?ν6 and ν6 has been estimated to be 0.15?±?0.02. High-quality ab initio calculations have also been performed at the CCSD(T) level of theory in order to support the experimental investigation through the calculation of molecular parameters relevant to ro-vibrational spectroscopy. 相似文献
12.
High-resolution infrared spectrum of CHD279Br: ro-vibrational analysis of the ν5 and ν9 fundamentals
ABSTRACTThe high-resolution infrared spectrum of CHD279Br has been investigated by Fourier transform spectroscopy in the range 700–900?cm?1 at an unapodized resolution of 0.0035?cm?1. This spectral region is characterised by the absorptions of the ν5 (814.5185?cm?1) and ν9 (716.9649?cm?1) fundamental bands, corresponding to H–C–Br deformation and CD2 rocking modes, respectively. The ν5 vibration of symmetry species A′ gives rise to an a-/c-hybrid band with a predominant a-type component, while the ν9 mode of A′′ symmetry produces a b-type envelope. The spectral analysis resulted in the identification of 5290 (J′?≤?63 and Ka′?≤?13) and 1657 (J′?≤?53 and Ka′?≤?12) transitions for ν5 and ν9 bands, respectively. The assigned data were fitted using the Watson’s S-reduced Hamiltonian in the Ir representation and the v5?=?1 and v9?=?1 state parameters up to the quartic centrifugal distortion terms have been obtained. From spectral simulations the dipole moment ratio |Δμa/Δμc| of the ν5 band has been determined to be 1.4?±?0.1 while the intensity ratio between ν5 and ν9 fundamentals has been estimated to have a value of 4.3?±?0.5. 相似文献
13.
Pietro Tundo Fabio Aricò Guillaume Gauthier Agostino Baldacci 《Comptes Rendus Chimie》2011,14(7-8):652-655
In this work the synthesis of a tricyclic isosorbide derivative in moderate yield directly from the dicarboxymethyl isosorbide in a continuous-flow apparatus is reported. The tricyclic structure has been isolated as pure and fully characterized. This product confirms the potentiality of dimethylcarbonate (DMC) as dehydrating agent also for complicated structure and opens up further investigation and application of DMC chemistry on renewable starting materials. 相似文献
14.
R. Baldacci M. A. Boschetti N. Christofides S. Christofides 《Computational Management Science》2009,6(3):281-306
A relevant financial planning problem is the periodical rebalance of a portfolio of assets such that the portfolio’s total
value exhibits certain characteristics. This problem can be modelled using a transition graph G to represent the future state space evolution of the corresponding economy and mathematically formulated as a linear programming
problem. We present two different mathematical formulations of the problem. The first considers explicitly the set of the
possible scenarios (scenario-based approach), while the second considers implicitly the whole set of scenarios provided by the graph G (graph-based approach). Unfortunately, for both the formulations the size of the corresponding linear programs can be huge even for simple
financial problems. However, the graph-based approach seems to be a more powerful model, since it allows to consider a huge
number of scenarios in a very compact formulation. The purpose of this paper is to present both heuristic and exact methods
for the solution of large-scale multi-period financial planning problems using the graph-based model. In particular, in this
paper we propose lower and upper bounds and three exact methods based on column, row and column/row generation, respectively.
Since the methods based on column/row generation exploits simultaneously both the primal and the dual structure of the problem
we call it Criss-Cross generation method. Computational results are given to prove the effectiveness of the proposed methods.
相似文献
15.
The solution of a vehicle routing problem calls for the determination of a set of routes, each performed by a single vehicle
which starts and ends at its own depot, such that all the requirements of the customers are fulfilled and the global transportation
cost is minimized. The routes have to satisfy several operational constraints which depend on the nature of the transported
goods, on the quality of the service level, and on the characteristics of the customers and of the vehicles. One of the most
common operational constraint addressed in the scientific literature is that the vehicle fleet is capacitated and the total
load transported by a vehicle cannot exceed its capacity. 相似文献
16.
Pietropolli Charmet A Stoppa P Toninello P Baldacci A Giorgianni S 《Physical chemistry chemical physics : PCCP》2006,8(21):2491-2498
Pulsed slit-jet high resolution (up to 0.0009 cm(-1) FWHM) infrared diode laser spectra of CF(3)Br, with natural isotopic abundance, were obtained in the region around 9.2 microm at the rotational temperature of about 50 K. In addition, diode laser spectra at reduced temperature (200 K) were recorded. We present here the rovibrational analysis of the nu(1) fundamental in the range 1075-1090 cm(-1). The fine structure of many P(J) and R(J) clusters has been well resolved for the first time. The assignment of rovibrational transitions has been accomplished up to K = 27, J = 63 for CFBr and K = 33, J = 62 for CFBr. A total of 636 (CFBr) and 880 (CFBr) lines were used in the final fit and a very accurate set of molecular constants, including the quartic centrifugal distortion coefficients for the v(1) = 1 state of both the bromine isotopologues, was obtained. In addition, spectral features belonging to the nu(1) + nu(6)-nu(6) hot band were unambiguously identified and a set of spectroscopic parameters were determined. 相似文献
17.
The gas-phase infrared spectrum of the nu(4) fundamental band of CH(2)(79)BrF was recorded in the 1010-1116 cm(-1) wavenumber region using a TDL spectrometer. In this first high-resolution investigation of the synthesized (79)Br isotopic form, more than 10 200 transitions of this a/b-hybrid band centered at 1068.5385 cm(-1) were assigned and, using the Watson's A-reduced Hamiltonian in the I(r)-representation, a reliable set of molecular constants for the excited state v(4) = 1 was determined. From ground state combination differences having rotational quantum numbers J and K(a) up to 97 and 21, respectively, improved and extended ground state rotational and centrifugal distortion constants were calculated as well. Comparison between the observed and calculated band intensities in appropriate regions of the spectrum gave an estimate of the transition dipole-moment ratio along the a and b axes as ||Deltaμ(a)/Deltaμ(b) || = 2.0 +/- 0.2, in agreement with the predicted theoretical value of 1.99. Copyright 2000 Academic Press. 相似文献
18.
The high-resolution (0.0030 cm−1) Fourier transform infrared spectrum of CH279BrF has been studied in part of the atmospheric window between 910 and 980 cm−1, the region of the ν9 (935.847 cm−1) and ν5 + ν6 (961.239 cm−1) bands. The ν9 fundamental consists of a pseudo a-type band induced by Coriolis coupling with ν5 + ν6, in turn exhibiting a predominant a-type structure. Several interactions connecting these levels and the dark state 3ν6 have been assessed. The whole data set is treated using Watson’s A-reduced Hamiltonian in the Ir representation implemented with first order a- and b- and c-type Coriolis terms. A detailed analysis of the rotational structure yields a set of accurate upper-state parameters up to quartic distortion terms for ν9 and ν5 + ν6. In addition, spectroscopic information about the dark ternary overtone of ν6 has been obtained. 相似文献
19.
Cazzoli G Cludi L Puzzarini C Stoppa P Pietropolli Charmet A Tasinato N Baldacci A Baldan A Giorgianni S Wugt Larsen R Stopkowicz S Gauss J 《The journal of physical chemistry. A》2011,115(4):453-459
A combined microwave, infrared, and computational investigation of CHBrF(2) is reported. For the vibrational ground state, measurements in the millimeter- and sub-millimeter-wave regions for CH(79)BrF(2) and CH(81)BrF(2) provided rotational and centrifugal-distortion constants up to the sextic terms as well as the hyperfine parameters (quadrupole-coupling and spin-rotation interaction constants) of the bromine nucleus. The determination of the latter was made possible by recording of spectra at sub-Doppler resolution, achieved by means of the Lamb-dip technique, and supporting the spectra analysis by high-level quantum chemical calculations at the coupled-cluster level. In this context, the importance of relativistic effects, which are of the order of 6.5% and included in the present work using second-order direct perturbation theory, needs to be emphasized for accurate predictions of the bromine quadrupole-coupling constants. The infrared measurements focused on the ν(4) fundamental band of CH(79)BrF(2). Fourier transform investigations using a synchrotron radiation source provided the necessary resolution for the observation and analysis of the rotational structure. The spectroscopic parameters of the v(4) = 1 state were found to be close to those of the vibrational ground state, indicating that the ν(4) band is essentially unaffected by perturbations. 相似文献
20.