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1.
Pangavhane SD Hebedová L Alberti M Havel J 《Rapid communications in mass spectrometry : RCM》2011,25(7):917-924
Phosphorus nitride clusters generated during Laser Desorption Ionization (LDI) and Matrix-Assisted Laser Desorption Ionization (MALDI) of solid P(3) N(5) were analyzed via Time-of-Flight Mass Spectrometry (TOF MS). The LDI TOF mass spectra show the formation of series of clusters: P(m)N(n)(+) {(m=1; n=8-11), (m=4; n=3-4), (m=5; n=1-5), (m=6; n=1-3, 5-8), (m=2-7; n=1), (m=5-10; n=2), (m=4-6; n=3), (m=4,5; n=4), (m=5,6; n=5)}, and P(m)N(n)(-) (m=4,5; n=1). Using 3-hydroxypicolinic acid (HPA) as a matrix the P(m)N(n)(+) species (m=1-4, 6, 8) with a high nitrogen content (n=4, 5, 8, 10-12, 20) were identified. The formation of a N(6)(-) cluster was also detected using a C(60) matrix. Under various conditions singly charged P(m)(+) (m=2-7, 9, 13), P(m)(-) (m=3-11, 13, 15, 17), N(n)(+) (n=5, 9, 10, 12, 13), and N(n)(-) (n=6, 10-15) clusters were identified in the mass spectra. Such high nitrogen content clusters (up to N(15)(-)) generated by laser desorption from a solid material are described for the first time. The stoichiometry of the P(m)N(n) clusters was determined via isotopic envelope analysis and computer modelling. The composition of the clusters with respect to the crystalline structure of α-P(3)N(5) is discussed. 相似文献
2.
Time-resolved laser flash photolysis and pulse radiolysis have been used to study the chemical activity of podophyllotoxin(PPT) and etoposide(VP-16). The mechanism of photoioniza-tion of etoposide and podophyllotoxin has been confirmed and illustrated. It is demonstrated that VP-16 and PPT in aqueous solution can be photoionized at 248 nm to give hydrated electron and neutral radical resulting from rapid deprotonation of radical cation of VP-16 and PPT. The quantum yield for the photoionization of VP-16 and PPT with single-photo is 0.21 and 0.61, respectively. In addition, they can react with hydrated electron, hydrogen radical and hydroxyl radical. This will give chemists some advice on synthesizing new derivatives of podophyllotoxin in cancer treatment. 相似文献
3.
Hong Shui-Li 《结构化学》1994,(1)
RamanSpectraofLaserCrystalsNABandNYABandtheLigandVibrationsofTheirActiveIons¥HongShui-Li(DepartmentofPhysics,FuzhouUniversity... 相似文献
4.
Xiao Qiang YU Xian ZHANG Gui Bao XU Hua Ping ZHAO Wei HE Zong Shu SHAO Xian Gang XU Min Hua JIANG 《中国化学快报》2006,17(1):81-84
The research on up-conversion photoluminescence of organic materials is a hot topic1, most recently, the up-conversion laser properties of organic materials with big two- photon absorption cross section have been noticed especially2. According to the prev… 相似文献
5.
A Raman spectroscopic study was carried out on water in gelatin at 4% w/v in gel (25 °C) and sol (40–60 °C) states at various
concentrations (0.5, 1, 5, 10 and 15 mM) of anionic surfactant, sodium dodecyl sulfate (SDS). The in-phase collective stretching
mode vibration of hydrogen-bonded -OH oscillators, centered around 3250 cm−1 in a tetrahedral network of water molecules, was observed to be significantly affected by temperature and the presence of
SDS. According to our observation this may be due to the thinning of the hydration water around the gelatin molecules due
to strong thermal agitation. The peak center of the collective bands of water decreased linearly with SDS concentration in
the gel state which implied that with the increase in concentration of SDS, the -OH oscillators gradually lost their attachment
to gelatin chains and were replaced by SDS molecules. Ultimately this resulted in a thinning of the hydration layer around
the gelatin and the oscillation frequency of -OH oscillators moved towards 3250 cm−1 at 1 mM SDS concentration resulting in increased coupling of -OH oscillators to form the tetrahedral network at the critical
micelle concentration (cmc) of SDS. The variation in the peak amplitudes and the systematic reversal of their trend about
the cmc axis was surprising. At 40 °C the amplitude of the peak at 3250 cm−1 increased drastically due to a possible coil expansion by about 7–8% which accommodated more interstitial water into the
pseudonetwork leading to an increase in the number of nearest neighbors and for about 6% increase in the C value. However, at the cmc the peak amplitude was observed to be independent of temperature. Continuous shifting of the peak
center and full width at half-maxima towards lower values was observed with increasing SDS concentrations in the gel state.
Received: 28 September 1998 Accepted in revised form: 8 March 1999 相似文献
6.
ZHANG Shu-dong LI Hai-Yang ** . Laboratory of Environmental Spectroscopy Anhui Institute of Optics Fine Mechanics Chinese Academy of Sciences Hefei P. R. China . Graduate School of the Chinese Academy of Sciences Beijing P. R. China . Physics Electronic Engineering College Northwest Normal University Lanzhou P. R. China 《高等学校化学研究》2003,19(3):320-323
IntroductionLaser ablation has been applied broadly toplasma production,cluster formation,nanometermaterial and thin film material preparation[1,2 ] .Us-ing spectroscopic technique and mass spectrometryto identify the transient species formed in the pro-cess could provide much useful information aboutthe prosperity ofplasma,the mechanism of materi-al growth[3 ,4] .Aluminum is an important metal material andwidely used in industry and daily life. To study thereaction mechanism of Al atoms with… 相似文献
7.
The structures of 17β-estradiol (estradiol) and its 1:1 cluster with water have been investigated in supersonic jets. The S(1)-S(0) electronic spectrum of estradiol monomer shows four strong sharp bands in the 35050-35200 cm(-1) region. Ultraviolet-ultraviolet hole-burning (UV-UV HB) and infrared-ultraviolet double-resonance (IR-UV DR) spectra of these bands indicate that they are due to four different conformers of estradiol originating from the different orientation of the OH groups in the A- and D-rings. The addition of water vapor to the sample gas generates four new bands in the 34700-34800 cm(-1) region, which are assigned to the estradiol-H(2)O 1:1 cluster with the A-ring (phenyl ring) OH acting as a hydrogen(H)-bond donor. In addition, we found very weak bands near the origin bands of bare estradiol upon the addition of water vapor. These bands are assigned to the isomers of estradiol-H(2)O 1:1 cluster having an H-bond at the D-ring OH. We determine the conformation of bare estradiol and the structures of its monohydrated clusters with the aid of density functional theory calculation and discuss the relationship between the stability of hydrated clusters and the conformation of estradiol. 相似文献
8.
References: 《分析测试学报》2001,20(Z1):12-13
Unusual amine - bond fragmentation on the peptide/protein backbone has been reported using matrix - assisted laser desorption/ionization time - of- flight mass spectrometry (MALDI - TOFMS)The amine - bond cleavage occurred without metastable decay, while the peptide - bond cleavage occurred with metastable decay of peptide ions in a drift region of TOF mass analyzer. It was presumed that the amine - bond cleavage occurred as a non - ergodic process independent of the ionization under MALDI conditions. 相似文献
9.
Mahmood Akhtar Abdul Jabbar Shaukat Mahmood Zeshan Adeel Umar Rizwan Ahmed 《Analytical letters》2019,52(14):2312-2328
The qualitative and quantitative analysis of soil samples collected from Sialkot, Pakistan (which contains leather industrial plants), has been performed using laser-induced breakdown spectroscopy (LIBS) and laser ablation time of flight mass spectrometry (LA-TOF-MS). The focused beam of a Q-switched Nd: YAG laser (532?nm) was used to ablate the soil samples in air at atmospheric pressure. The optical emission spectra demonstrate the presence of the spectral lines of Si, Fe, Al, Ca, Ti, K, Cr, Mg, Na, Ba, and Li in all of the samples. The emission lines intensities, electron number densities, and excitation temperatures were significantly enhanced in the presence of an external 0.3 T magnetic field applied perpendicular to the plasma plume. A maximum enhancement factor of approximately 8 was observed in the emission intensity. The emergence of several additional lines has also been detected using the magnetic field-assisted LIBS approach. The elemental composition determined using calibration-free laser-induced breakdown spectroscopy (CF-LIBS), with and without magnetic field, reveals that the external magnetic field only adjusts the laser-generated plasma dynamics without affecting the quantitative analysis of the samples. Importantly, the toxic and heavy elements such as chromium and barium were detected and quantified in all of the soil samples by both of these techniques. The variations in the compositional analysis using CF-LIBS with and without the applied magnetic field and LA-TOF-MS were less than 10%. 相似文献
10.
Marzieh Jazaeri Parviz Torkzaban Saeid Afshar Roya Najafi-Vosough Praveen Arany Leila Gholami 《Photochemistry and photobiology》2023,99(3):1003-1009
Gingival fibroblasts have critical roles in oral wound healing. Photobiomodulation (PBM) has been shown to promote mucosal healing and is now recommended for managing oncotherapy-associated oral mucositis. This study examined the effects of the emission mode of a 940 nm diode laser on the viability and migration of human gingival fibroblasts. Cells were cultured in a routine growth media and treated with PBM (average power 0.1 W cm−2, average fluence 3 J cm−2, every 12 h for six sessions) in one continuous wave and two pulsing settings with 20% and 50% duty cycles. Cell viability was assessed using MTT, and digital imaging quantified cell migration. After 48 and 72 h, all treatment groups had significantly higher viability (n = 6, P < 0.05) compared with the control. The highest viability was seen in the pulsed (20% duty cycle) group at the 72-h time point. PBM improved fibroblast migration in all PBM-treated groups, but differences were not statistically significant (n = 2, P > 0.05). PBM treatments can promote cell viability in both continuous and pulsed modes. Further studies are needed to elucidate the optimal setting for PBM-evoked responses for its rationalized use in promoting specific phases of oral wound healing. 相似文献
11.
A selective and sensitive method for determination of platinum and palladium(Ⅱ)in an aqueous solution simultaneously by laser thermal lens spectrometry,based on the complex reaction of 2-(3,5-dichloropyridylazo)-5-dimethylaminoamiline(3,5-diCl-PADMA) with platinum and palladium,has been developed.It is shown that the palladium complex can be fromed at room temperature, while the platinum complex can be only formed after being heated in a boiling water bath.By using this difference of reaction temperature and the characteristic of the complexes mentioned above,the method for simultaneous determination of platinum and palladium was established in an aqueous solution without a pre-separation.The results show that the dynamic linear ranges of determination for platinum and palladium are 0.005-0.04μg/mL and 0.005-0.25μg/mL respectively,and that the detection limits are both 0.002/μg/mL.The method has been applied to the determination of platinum and palladium simultaneously in alloy and catalyst samples with satisfactory results. 相似文献
12.
lnrecentyears,phot0chromicc0mpoundshaveattractedincreasingattentionduetotheirpotentialapplicati0ninopticaldatast0rage'.Amongthem,1,2-diarylethenesc0nstituteanimp0rtantclassowingtotheirbistationarystatesthermalstabilityandfatigueresistance2.Mucheffortshavebeens0farpaidtosynthesizethematerialsthatabsorbnear-infraredlightinordertoachievecompatibilitywithconventi0nalinfrareddiodelaser(Xse0.8um)usedincompactdiscsystem.Mostoftheclosedf0rms0ftherep0rtedsynthesizeddiaryletheneshavetheirabsorPtionmaxim… 相似文献
13.
IntroductionItisanimportantresearchtopictodeterminedirectlythecomponentsofacomplexsystemwithoutapriorsepa ration .Byutilizingthedifferencesofreactionconditionofthemetalionswithchromogenicreagent (temperatureoracidity)orthedifferentcharacteristicsoftheco… 相似文献
14.
《Spectrochimica Acta Part B: Atomic Spectroscopy》1998,53(13):1815-1825
The combination of an échelle spectrometer with a time-gated intensified charge coupled device (ICCD) camera for simultaneous measurements of spectral lines in wide ranges of the optical spectrum is presented. The analytical and diagnostic power of the échelle-ICCD combination is demonstrated by laser induced breakdown spectrometry (LIBS) of solid samples. The apparatus allows complete elemental analysis by single shots as the spectral lines of major, minor and trace constituents are measured simultaneously. The analytical precision and detection limits in single shot measurements are improved by the evaluation of many lines for each element. Further, plasma parameters, such as the plasma temperatures, can be determined from the same spectrum and, if necessary, used for normalization of the analyte line intensities. 相似文献
15.
MA Jian-hua LIN Wei-zhen HAN Zhen-hui YAO Si-de LIN Nian-yun . College of Biology Engineering Jimei University Xiamen P. R. China . Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai P. R. China 《高等学校化学研究》2006,22(3)
Introduction ElectrontransferoxidationofDNAbytripletartifi cialphotonucleaserevealsabrightprospectofitsappli cationinbiologyandmedicine.Bothmolecularorbital calculationandlaserexperimentshaveindicatedthat thehomoguaninesequenceshouldbethefinallocaliza tio… 相似文献
16.
A new LC - MSinterface was developed.Strong ion signals were obtained when aqueous or water/methanolsample solution effusing out of the stainless steel capillary was irradiated by thefocused infrared laser.Generally the ion signals obtained by this method laser spray are greater than those by electrospray especially in the negative- mode operation.…… 《分析测试学报》2001,20(Z1):138-139
A new LC - MS interface was developed.Strong ion signals were obtained when aqueous or water/methanol sample solution effusing out of the stainless steel capillary was irradiated by the focused infrared laser.Generally, the ion signals obtained by this method, laser spray, are greater than those by electrospray, especially in the negative- mode operation. 相似文献
17.
MA Jian-hua LIN Wei-zhen HAN Zhen-hui YAO Si-de LIN Nian-yun 《高等学校化学研究》2006,22(3):397-399
Introduction
Electron transfer oxidation of DNA by triplet artificial photonuclease reveals a bright prospect of its application in biology and medicine. Both molecular orbital calculation and laser experiments have indicated that the homo guanine sequence should be the final localization site of photoexcited hole via long range migration within DNA. However, the direct observation of the produced ion pairs of biomolecules especially the stabilized radical cation DNA or its components is hampered by the overwhelming transient absorption of protonated radical anion of photosensitizers, such as 2-methyl-1,4-naphthaguinonel (MQ). 相似文献
18.
Terashkevich V. A. Meshkov V. V. Pazyuk E. A. Stolyarov A. V. 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(4):756-759
Russian Journal of Physical Chemistry A - The pair interaction potentials of the weakly bound Rb–CH4 and Cs–CH4 systems, which are active media of alkali metal vapor lasers with... 相似文献
19.
Chunyong Liang Baofa Li Hongshui Wang Baoe Li Jianjun Yang Linxi Zhou 《Journal of Dispersion Science and Technology》2014,35(9):1345-1350
An excellent hydrophobic and super-oleophilic surface on 316 L stainless steel was obtained by femtosecond laser irradiation in deionized water. Using lower laser fluence and scanning speed of femtosecond laser irradiation, a single stripe structure was fabricated and the corresponding contact angle to water and ethylene glycol was 127.2° and 19.6°, respectively. When laser fluence and scanning speeds increased, stripes, grooves, and holes structures were obtained on the surface and the corresponding water contact angles increased and ethylene glycol contact angles decreased, with a maximum water contact angle of 142.5° and minimum ethylene glycol contact angle of 6.4°. 相似文献
20.
The laser-induced crystallization method is applied to pattern two-dimensional planar β-BaB2O4 crystals on the surface of Sm2O3–BaO–B2O3 glass. By scanning Yb:YVO4 fiber lasers (wavelength: 1080 nm) continuously with a small step (0.5 μm) between laser irradiated areas, homogeneous planar β-BaB2O4 crystals are patterned successfully, and a preferential growth orientation of β-BaB2O4 crystals is confirmed from linearly polarized micro-Raman scattering spectrum and second harmonic intensity measurements. It is found that the crystal growth direction is perpendicular to the laser scanning direction. This relation, i.e., the perpendicular relation, is different from the behavior in discrete crystal line patterning, where the crystal growth direction is consistent with the laser scanning direction. The present study proposes the possibility of the control of crystal growth direction in laser-induced crystallization in glasses. 相似文献