Centrifugal Constants Research Articles

Effect of ultrasonic pretreatment on the structure and emulsion stability of epigallocatechin-3-gallate and rice bran protein complex

To enhance the emulsion stability of RBP, the mixed solution of epigallocatechin-3-gallate (EGCG) and rice bran protein (RBP) was pretreated by increasing ultrasonic power (200–500 W). Ultrasonic pretreatment decreased the α-helix/β-sheet ratio (P < 0.05), and caused red-shift absorption peaks of intrinsic fluorescence and UV absorption spectroscopy of EGCG-RBP complex. With increasing ultrasonic power, combined phenol content, particle size, absolute value of ζ-potential, free –SH content, and surface hydrophobicity of EGCG-RBP complex initially rose, and subsequently dropped (P < 0.05). Compared with the EGCG-RBP complex without ultrasonic pretreatment, emulsifying activity index increased from 37.68 m2/g to 42.51 m2/g, and emulsion stability index increased from 123.00 min to 326.43 min as ultrasonic power was 425 W. The centrifugal stability constant, emulsion separation rate, and emulsion particle size initially dropped, and subsequently rose with increasing ultrasonic power. The emulsion stability of EGCG-RBP complex was correlated with particle size, absolute value of ζ-potential, α-helix/β-sheet ratio, free –SH content, and surface hydrophobicity (P < 0.05). Overall, ultrasonic pretreatment enhanced the EGCG-RBP interaction by regulating the absolute value of ζ-potential, flexibility and surface hydrophobicity of EGCG-RBP complex, thus improving emulsion stability, which provided a theoretical foundation for expanding the application of RBP in foodstuffs.

Rovibrational Energies of 13C16O2 Determined with Kilohertz Accuracy.

Accurate spectroscopic data of carbon dioxide are widely used in many important applications, such as carbon monitoring missions. Here, we present comb-locked cavity ring-down saturation spectroscopy of the second most abundant isotopologue of CO2, 13C16O2. We determined the positions of 88 lines in three vibrational bands in the 1.6 μm region, 30011e/30012e/30013e-00001e, with an accuracy of a few kHz. Based on the analysis of combination differences, we obtained for the first time the ground-state rotational energies with kHz accuracy. We also provide a set of hybrid line positions for 150 13C16O2 transitions. The rotational energies (J < 50) in the 30013e vibrational state can be fitted by a set of rotational and centrifugal constants with deviations within a few kHz, indicating that the 30013e state is free of perturbations. These precise isotopic line positions will be utilized to improve the Hamiltonian model and quantitative remote sensing of carbon dioxide. Moreover, they will help to track changes in the carbon source and sink through isotopic analysis.

Effect of WPI/Tween 80 mixed emulsifiers on physicochemical stability of ginsenosides nanoemulsions

Conversion of major ginsenosides into minor ginsenosides improves its pharmacological effects. This study managed to convert major ginsenosides into minor ginsenoside Rg3 and compound K (CK) by optimizing acidolysis conditions (pH, incubation temperatures and time) and evaluated the effects of the whey protein isolate (WPI)/Tween 80 ratio on the physicochemical properties of ginsenoside nanoemulsions. The optimal conditions for acidolysis are incubation at 110 °C for 3 h at a pH of 2.0, whereafter the yield of ginsenoside Rg3 and CK was 2.16 mg/g and 2.80 mg/g, respectively. For the ginsenoside nanoemulsions with 0.5% WPI as emulsifier, as Tween 80 increased from 0.1% to 0.5%, the mean droplet diameter gradually decreased from ∼740 nm to ∼310 nm. Accordingly, the encapsulation efficiency of Rg3 and CK increased by 8.36% and 9.03%, respectively, and the centrifugal stability constant increased by 49.82%. These results showed that nanoemulsion prepared with 0.5% WPI and 0.5% Tween 80 exhibited higher encapsulation efficiency and physicochemical stability. In addition, ginsenoside nanoemulsion prepared with 0.5% WPI and 0.5% Tween 80 showed great industrial applicability during freeze-thaw cycles, heat treatments and storage. Generally, the incorporation of Tween 80 as a co-emulsifier improved the encapsulation efficiency and physicochemical stability of WPI-stabilized ginsenoside nanoemulsions, which may improve its bioaccessibility, by stabilizing ginsenoside emulsions during further processing, such as during thermal pasteurization and microencapsulation.

Preparation, Characterization, Evaluation of Neuroprotective Effect, and Related Mechanisms of Phosphatidylserine Emulsion in 5- and 12-Week Old Mice.

Phosphatidylserine (PS) improves learning and memory capacity. In this study, PS formulation was optimized by a response surface methodology. Moreover, we found that PS not only functions as a biologically active component in food preparations but also improves the emulsion's physical stability. Our results showed that the PS emulsions are characterized by a smaller particle size, higher ζ-potential (negative), higher viscosity, and lower surface tension and centrifugal stability constants than the emulsion without PS. Furthermore, we explored the neuroprotective effects of PS emulsion and its underlying mechanisms. Treatment with 2% (w/w) PS emulsion for three months enhanced spatial learning and memory in 5- and 12-week old mice in the Morris water maze test. Western-blotting analysis displayed that the 2% (w/w) PS emulsion treated group upregulated BDNF, TrkB, PSD95, mTOR, MBP, and ErbB4 expression in the hippocampus of 5- and 12-week old mice. Reverse transcription polymerase chain reaction (RT-PCR) analysis revealed elevated Nrg-1 and ErbB4 mRNA expression in the 2% (w/w) PS emulsion treated groups, and high Nrg-1 and ErbB4 expression levels were associated with better myelination. In conclusion, we reported PS emulsions with high stability and high bioavailability. Meanwhile, 2% (w/w) PS emulsion enhances learning, memory, and myelination in mice by activating the BDNF/TrkB and Nrg-1/ErbB4 signaling.

Effect of Dihydropyridine Enrichment in the Microstructure of the Palisade Layer on the Stability of Fat Nano-emulsions.

Relationship between the stability of fat nano-emulsions and the incorporated drug at the molecular level are rarely known. Herein, fat nano-emulsions containing dihydropyridine drugs were prepared and the microstructure of their palisade layers were investigated.The prepared 1.0mg/mL nimodipine nano-emulsion was found to contain 65.50% drug in the palisade layer. The increasing drug concentration led to a decrease-increase-decrease trend in centrifugal stability constant, particle size and proton nuclear magnetic resonance (1H NMR) signal intensity of the lecithin trimethyl ammonium group in the nimodipine and felodipine nano-emulsions. The 1H NMR spectra of test solutions including nano-emulsions suggest that increasing drugs penetrated into the palisade layer, resulting in the lecithin arrangement from loose to tight, and then from monolayer to bilayer. Nimodipine and felodipine nano-emulsions showed two valley values at concentrations of 0.15 and 0.75mg/mL, and 0.30 and 0.90mg/mL respectively, which indicated that the nano-emulsion has two more stable states corresponding to the tightly arranged mono- and bi-palisade layer. These two concentrations are positively correlated with lipophilicity of nimodipine and felodipine. Further, nimodipine liposomes were prepared to validate the effect of drugs on the arrangement of lecithin in the palisade layer. 1H NMR characterizations of the liposomes showed a similar profile to that of nano-emulsions. These results demonstrated that the increasing drug concentration could cause a rearrangement of lecithin in the palisade layer, thus affecting emulsion stability.

ВРАЩАТЕЛЬНЫЕ СПЕКТРЫ РЯДА ПОЛИЦИКЛИЧЕСКИХ АРОМАТИЧЕСКИХ УГЛЕВОДОРОДОВ

A theoretical study of the rotational spectra of a number of polycyclic aromatic hydrocarbons (PAHs) was carried out on the basis of quantum-chemical calculations by PRIRODA program in the PBE/3ζ approximation. Calculations are given for neutral molecules, their radical anions and radical cations in the rigid top approximation. Twelve neutral PAHs under study have no dipole moment and are not of interest for rotational spectroscopy. Thirteen neutral PAHs have a dipole moment not exceeding 0.09 Debye and, under certain conditions, can be studied in the microwave region. The remaining six compounds are PAHs with methyl and phenyl substituents, their dipole moments are 0.32-0.65 Debye, which makes it possible to study their microwave spectrum. For radical ions, the situation with the dipole moment is as follows: if a neutral molecule does not have a dipole moment, then the corresponding radical ion does not have it either; if the dipole moment of a neutral molecule is nonzero, then for radical ions it increases at least several times. For example, in the benzo [b] chrysene radical anion, the μa-component component of the dipole moment increases by 250 times, the μb-component by 7 times, and the total dipole moment by about 100 times. This effect is more pronounced for radical anions than for radical cations. In this case, it becomes possible to detect the spectrum of if not a neutral molecule, then at least one of its charge states. For a number of compounds, the patterns of various spectroscopic parameters depending on the number of carbon atoms in PAHs were found. In the B3LYP/6-31G(d,p) approximation, quartic centrifugal distortion constants were calculated for five compounds, and their effect on the rotational spectrum was estimated: for many compounds under study, they can have a significant effect on the microwave spectrum. With an increase in PAHs, the centrifugal constants decrease indicating an increase in the rigidity of the molecules. Thus, substituted neutral PAHs, as well as a number of radical ions, may be of interest for experimental studies in laboratory conditions and in space.

Influence of Long-Chain/Medium-Chain Triglycerides and Whey Protein/Tween 80 Ratio on the Stability of Phosphatidylserine Emulsions (O/W).

Phosphatidylserine (PS) is a major anionic phospholipid constituent of membrane bilayers, which is specifically enriched in the cytoplasmic leaflet, has functions of regulating the intracellular signaling pathways of neuronal survival and differentiation, and acts as a neurotransmitter to control the activity of neurons. Oil-in-water (O/W) emulsions could improve the bio-availability of PS. Thus, there is a high level of interest in PS emulsion because of its purported health benefits. However, because of high viscosity and poor fluidity, it remains difficult to make the emulsion. A detailed analysis with suited biophysical methods would help to better understand the processes on a molecular level. Therefore, the main aim of the present study was to engineer and characterize a stable O/W phosphatidylserine emulsion. Furthermore, the effect of emulsifiers mixture, whey protein isolate (WPI), and Tween 80 (T80), as well as the oil phase was systematically evaluated. The key parameters were the chain length and the degree of nonsaturation (sunflower oil, a long-chain triglycerides [LCTs] or a medium-chain triglycerides [MCTs]). Small droplets of emulsions could be obtained by adjusting the type of emulsifier and the LCT/MCT ratio. A stable PS emulsion characterized by a smaller droplet size, higher negative zeta-potential, lower centrifugal stability constant, and longer storage time was produced by MCTs T80 (2.0%, w/w) with T80 (2.0%, w/w) as the emulsifier, and by LCTs with the WPI (0.5%, w/w)—T80 (1.5%, w/w) as the emulsifier, respectively. The PS emulsion with LCTs exhibited higher viscosity, when compared to the emulsion made by MCT at the same emulsifier concentration, while all emulsions exhibited a shear thinning behavior. The microstructure images revealed that the PS emulsions produced by MCTs and T80 (2.0%, w/w) or WPIs (0.5%, w/w)—T80 (1.5%, w/w) mixed with LCTs can form specific uniform networks, in order to prevent flocculation. After 28 days of storage, no visual phase separation was observed in the emulsions, except for the PS emulsion with the WPI (2.0%, w/w). It was concluded that the characteristics of the interfacial layer of particles in the PS emulsion system were not only dependent on the proportion of the applied emulsifiers, but also dependent on the oily phase features. These findings may provide indications for choosing the suitable process parameters when a stable PS emulsion is produced.

Structure of the model grignard-type reagent ClZnCH3 ([formula omitted]1A1) by millimeter-wave spectroscopy

Pure rotational spectra of the 37ClZnCH3, ClZnCD3, and ClZn13CH3 isotopologues of monomeric ClZnCH3 (X̃1A1) have been recorded using millimeter-wave direct absorption techniques in the frequency range 263–303 GHz. These species were synthesized in the gas phase in a DC discharge by the reaction of zinc vapor, produced in a Broida-type oven, with 37ClCH3 (in natural chlorine abundance), ClCD3, or Cl13CH3. Five to eight rotational transitions J + 1 ← J consisting of K ladder structure were measured for each isotopologue, identifying all three species as prolate symmetric tops. The data for each isotopologue were analyzed with a symmetric top Hamiltonian and rotational and centrifugal constants determined. In combination with previous measurements of Cl64ZnCH3, Cl66ZnCH3, and Cl68ZnCH3, an rm(2) structure was determined for this organozinc compound. The bond lengths in ClZnCH3 were calculated to be rCl-Zn = 2.0831(1) Å, rZn-C = 1.9085(1) Å, and rC-H = 1.1806(5) Å, considerably different from those established from crystal structures of related species ClZnCH2CH3 and ClZnEtTMEDA. The HCH bond angle was found to be 110.5° – slightly larger than that in methane. These data serve to benchmark future structure calculations of organozinc compounds, which are widely used in organic synthesis.

Conformational landscape and inertial defect of methoxyphenol isomers studied by mm-wave spectroscopy and quantum chemistry calculations.

Because methoxyphenols (MP) are emitted in significant quantities during biomass fires and contribute to the secondary organic aerosols formation which impacts the climate, their gas phase monitoring in the atmosphere is crucial and requires accurate rovibrational cross sections determined with a good knowledge of their ground state (GS) and vibrationally excited state (ES) molecular parameters. Therefore, the rotational spectra of the two isomers, 2-MP (guaïacol) and 4-MP (mequinol), have been measured in absorption and in emission at room temperature using a frequency multiplication chain and a mm-wave Fourier transform chirped-pulse spectrometer, respectively. Guided by quantum chemistry calculations, the conformational landscape has been characterised and the observation of only one rotamer in the spectra of 2-MP and 4-MP has been explained. For 2-MP, the most stable conformation is justified by an intramolecular O-H⋯OCH3 hydrogen-bond which has been characterised by a topology analysis of the electron density. In a global fit including more than 30 000 line assignments, rotational and quartic centrifugal constants of the GS and the three lowest energy ES have been determined allowing to reproduce the millimeter-wave spectra at the experimental accuracy. The same work has been performed on the cis-rotamer of 4-MP highlighting some perturbations marring the fit quality for two vibrationally ES. Finally, the isomeric dependence of the negative inertial defect ΔI agrees with that of the lowest energy out of plane mode ν45, and the variation of ΔI with the degree of vibrational excitation allows a fine estimation of v45 = 1 vibrational wavenumber.

Mono, di, tri and tetraethylene glycol: Spectroscopic characterization using density functional method and experiment

We report infrared and electronic absorption spectra of mono, di, tri and tetra ethylene glycol (EG) in gas phase, their cation and anion and in water solvent using density functional theory calculations at B3LYP/TZVP level. Structural paramaters, rotational and centrifugal distortional constants and dipole moments are also reported. A siginificant shifts in vibrational frequencies and peaks in electronic absorption spectra have been observed upon ionization of mono, di, tri and tetra ethylene glycols. We have also obtained experimental vibrational spectrum of monoethylene glycol. Vibrational frequencies of mono ethylene glycol from theory and experiment are compared. We have used integral equation formalism polarizable continuum model (IEFPCM) model to study the influence of water solvent on vibrational frequencies of neutral mono, di, tri and tetra ethylene glycol. Electronic absorption spectra for these molecules have been obtained using Time dependent density functional theory (TDDFT).

Resonance rotational level crossing in the fluorosulfate radical FSO3[rad] and experimental determination of the rotational A and the centrifugal distortion DK constants

The resonance crossing of rotational levels with different fine-structure components and different k rotational quantum numbers was observed in the rotational spectra of the symmetric top fluorosulfate radical FSO3. Detailed measurements were performed to analyze these weak resonances as well as the A1–A2 splittings of the K = 3 and K = 6 transitions. The resonance level crossing enabled the experimental determination of “forbidden” parameters, the rotational A and the centrifugal distortion DK constants as well as the corresponding resonance off-diagonal matrix element.

NEW QUANTUM APPROACH TO DETERMINATION OF THE MOLECULAR SPECTRAL CONSTANTS AND PROBABILITIES FOR COOPERATIVE VIBRATIONROTATION-NUCLEAR TRANSITIONS IN SPECTRA OF DIATOMICS AND THE HADRONIC MOLECULES

It is proposed a new approach to construction of the potential function of diatomic molecules as a sum of the known perturbed Morse oscillator function, the Simons-Parr-Finlan molecular potential in the middle of the potential curve, function of the -Cn/Rn type at the large internuclear distances. Within this approach it is presented a precise scheme for computing the molecular spectral parameters, namely, vibrational, rotational, centrifugal constants for the electronic states of diatomics. As application it was carried out calculation of the of molecular constants (cm-1) for the X1Σ+ B1Π states of the KRb dimer and rubidium dimer and performed further comparison with experimental data. Within consistent approach to calculation of the electron-nuclear γ transition spectra (set of vibrationrotational satellites in molecule) of molecule there are obtained the estimates for vibration-rotationnuclear transition probabilities in a case of the emission and absorption spectrum of nucleus 127I(E(0)g = 203 keV) in the molecule of H127I for different approximations of the for potential curves: the hadmonic oscillator, the Dunham model and presented approach.

The research about microscopic structure of emulsion membrane in O/W emulsion by NMR and its influence to emulsion stability

PurposeThis paper discussed the influence of microstructure of emulsion membrane on O/W emulsion stability. MethodsO/W emulsions were emulsified with equal dosage of egg yolk lecithin and increasing dosage of co-emulsifier (oleic acid or HS15). The average particle size and centrifugal stability constant of emulsion, as well as interfacial tension between oil and water phase were determined. The microstructure of emulsion membrane had been studied by 1H/13C NMR, meanwhile the emulsion droplets were visually presented with TEM and IFM. ResultsWith increasing dosage of co-emulsifier, emulsions showed two stable states, under which the signal intensity of characteristic group (orient to lipophilic core) of egg yolk lecithin disappeared in NMR of emulsions, but that (orient to aqueous phase) of co-emulsifiers only had some reduction at the second stable state. At the two stable states, the emulsion membranes were neater in TEM and emulsion droplets were rounder in IFM. Furthermore, the average particle size of emulsions at the second stable state was bigger than that at the first stable state. ConclusionsEgg yolk lecithin and co-emulsifier respectively arranged into monolayer and bilayer emulsion membrane at the two stable states. The microstructure of emulsion membrane was related to the stability of emulsion.

Centrifugal Distortion in the Microwave Spectrum of the Tt Conformer of the n-CH3CH2CH2OH Molecule

We have studied the microwave rotational spectrum of the Tt conformer of the propyl alcohol molecule n-CH3CH2CH2OH in the frequency range 37.0–78.0 GHz. Theoretical treatment of the spectrum was carried out using Watson′s A-reduced rotational Hamiltonian. We identified 78 rotational transitions with values of the rotational quantum number up to J = 37 inclusive. We have refined the rotational and centrifugal constants of the molecule.

Theoretical characterization of dimethyl carbonate at low temperatures.

Highly correlated ab initio methods (CCSD(T) and RCCSD(T)-F12) are employed for the spectroscopic characterization of the gas phase of dimethyl carbonate (DMC) at low temperatures. DMC, a relevant molecule for atmospheric and astrochemical studies, shows only two conformers, cis-cis and trans-cis, respectively, of C2v and Cs symmetries. cis-cis-DMC represents the most stable form. Using RCCSD(T)-F12 theory, the two sets of equilibrium rotational constants have been computed to be Ae = 10 493.15 MHz, Be = 2399.22 MHz, and Ce = 2001.78 MHz (cis-cis) and to be Ae = 6585.16 MHz, Be = 3009.04 MHz, and Ce = 2120.36 MHz (trans-cis). Centrifugal distortions constants and anharmonic frequencies for all of the vibrational modes are provided. Fermi displacements are predicted. The minimum energy pathway for the cis-cis → trans-cis interconversion process is restricted by a barrier of ∼3500 cm(-1). DMC displays internal rotation of two methyl groups. If the nonrigidity is considered, the molecule can be classified in the G36 (cis-cis) and the G18 (trans-cis) symmetry groups. For cis-cis-DMC, both internal tops are equivalent, and the torsional motions are restricted by V3 potential energy barriers of 384.7 cm(-1). trans-cis-DMC shows two different V3 barriers of 631.53 and 382.6 cm(-1). The far-infrared spectra linked to the torsional motion of both conformers are analyzed independently using a variational procedure and a two-dimensional flexible model. In cis-cis-DMC, the ground vibrational state splits into nine components: one nondegenerate, 0.000 cm(-1) (A1), four quadruply degenerate, 0.012 cm(-1) (G), and four doubly degenerate 0.024 cm(-1) (E1 and E3). The methyl torsional fundamentals are obtained to lie at 140.274 cm(-1) (ν15) and 132.564 cm(-1) (ν30).

Spectroscopic characterization of cysteine and methionine using density functional theory method

The present study reports theoretical infrared and electronic absorption spectra of neutral cysteine and methionine molecules in gas phase, their ions and in water ice. We also report infrared and electronic absorption spectra of nitrogen-substituted (in place of sulfur atom) cysteine and methionine. The geometrical parameters, dipole moments, rotational and centrifugal distortional constants for these molecules are reported at B3LYP/6-311++g(d,p) level of theory. A large change in vibrational and electronic absorption spectra has been observed upon ionization of cysteine and methionine. Calculated vibrational frequencies are compared with the available experimental frequencies for the neutral cysteine and methionine in gas phase. An influence of water ice on vibrational frequencies of neutral cysteine and methionine is studied using integral equation formalism polarizable continuum model (IEFPCM) at the same level of theory. Time Dependent Density Functional Theory (TDDFT) approach has been adapted to calculate the electronic absorption spectra of these molecules. The intense lines are suggested in order to detect these molecules in space.

Theoretical spectroscopic characterization at low temperatures of S-methyl thioformate and O-methyl thioformate.

Highly correlated ab initio methods are employed to determine spectroscopic properties at low temperatures of two S-analogs of methyl formate: S-methyl thioformate CH3-S-CHO (MSCHO) and O-methyl thioformate CH3-O-CHS (MOCHS). Both species are detectable and they are expected to play an important role in Astrochemistry. Molecular properties are compared with those of the O-analog, methyl formate. Both isomers present two conformers cis and trans. cis-CH3-S-CHO represents the most stable structure lying 4372.2 cm(-1) below cis-CH3-O-CHS. The energy difference between the cis and trans forms is drastically lower for MSCHO (1134 cm(-1)) than for MOCHS (1963.6 cm(-1)). Harmonic and anharmonic fundamentals and the corresponding intensities, as well as the rotational constants for the ground vibrational and first excited torsional states and the centrifugal distortions constants, are provided. Low torsional energy levels have been obtained by solving variationally a two dimensional Hamiltonian expressed in terms of the two torsional degrees of freedom. The corresponding 2D potential energy surfaces have been computed at the CCSD(T)/aug-cc-pVTZ level of theory. The methyl torsional barriers V3(cis) are determined to be 139.7 cm(-1) (CH3-S-CHO) and 670.4 cm(-1) (CH3-O-CHS). The A/E splitting of ground torsional state has been estimated to be 0.438 cm(-1) for CH3-S-CHO and negligible for CH3-O-CHS.

Submillimeter wave spectrum of sulfuric acid, H2SO4

The submillimeter spectrum of H2SO4 has been measured in selected regions up to 655.6GHz. The new measurements have been combined with available literature rotational data in a merged fit. This has resulted in an improved and extended set of rotational and centrifugal constants which accurately describe the spectrum well into the submillimeter region.

Properties of the B+-H2 and B+-D2 complexes: A theoretical and spectroscopic study

The rotationally resolved infrared spectrum of the B(+)-D(2) ion-neutral complex is recorded in the D-D stretch vibration region (2805-2875 cm(-1)) by detecting B(+) photofragments. Analysis of the spectrum confirms a T-shaped equilibrium geometry for the B(+)-D(2) complex with a vibrationally averaged intermolecular bond length of 2.247 Å, around 0.02 Å shorter than for the previously characterised B(+)-H(2) complex [V. Dryza, B. L. J. Poad, and E. J. Bieske, J. Am. Chem. Soc. 130, 12986 (2008)]. The D-D stretch band centre occurs at 2839.76 ± 0.10 cm(-1), representing a -153.8 cm(-1) shift from the Q(1)(0) transition of the free D(2) molecule. A new three dimensional ab initio potential energy surface for the B(+)+H(2) interaction is calculated using the coupled cluster RCCSD(T) method and is used in variational calculations for the rovibrational energies of B(+)-H(2) and B(+)-D(2). The calculations predict dissociation energies of 1254 cm(-1) for B(+)-H(2) with respect to the B(+)+H(2) (j = 0) limit, and 1313 cm(-1) for B(+)-D(2) with respect to the B(+)+D(2) (j = 0) limit. The theoretical approach reproduces the rotational and centrifugal constants of the B(+)-H(2) and B(+)-D(2) complexes to within 3%, and the magnitude of the contraction of the intermolecular bond accompanying excitation of the H(2) or D(2) sub-unit, but underestimates the H-H and D-D vibrational band shifts by 7%-8%. Combining the theoretical and experimental results allows a new, more accurate estimation for the B(+)-H(2) band origin (3939.64 ± 0.10 cm(-1)).

Study of the spectrum of the Kr-CO weakly bound molecular complex in the millimeter-wavelength range

The rotational spectrum of the weakly bound Kr-CO molecular complex formed in a pulsed molecular jet has been measured in the frequency range 112–150 GHz on an intracavity orotron-based spectrometer. The measured b-type transitions include the R branch of the band K = 1-0 with the rotational numbers J from 16 to 25 and the P branch of the band K = 2-1 with the rotational numbers J from 13 to 17. For the K = 1-0 band, we succeeded in recording transitions in complexes that consist of all stable Kr isotopes, i.e., 84Kr-CO, 86Kr-CO, 82Kr-CO, 83Kr-CO, and 80Kr-CO. For the K = 2-1 band, we observed transitions in the two most abundant isotopologues, 84Kr-CO and 86Kr-CO. The obtained data were used to determine the rotational and centrifugal constants of the Kr-CO complex.