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21.
An intensity-difference spectrum method is developed to disentangle the intensity volume effect inherent in focused laser beam interaction with gas-phase matter. This method is applicable to a Gaussian beam of constant axial intensity, which keeps the exact contribution from a predetermined intensity range and eliminates the contributions from lower intensities. We apply this method to the angularly resolved kinetic energy release spectrum of laser-induced dissociation of H2+. The difference spectrum at higher intensities is found to be dominated by the bond-softening process, and the distribution shifts to lower energy and becomes narrower with increasing intensity. 相似文献
22.
Webb Oren F. Phelps Tommy J. Blenkowski Paul R. Digrazia Philip M. Reed Gregory D. Applegate Bruce White David C. Sayler Gary S. 《Applied biochemistry and biotechnology》1991,28(1):5-19
Applied Biochemistry and Biotechnology - A bench scale experimental system was developed for the analysis of polycyclic aromatic hydrocarbon (PAH) degradation by mixed microbial cultures in PAH... 相似文献
23.
Amela Arnold Tobias J. Sherbow Amanda M. Bohanon Richard I. Sayler R. David Britt Allison M. Smith James C. Fettinger Louise A. Berben 《Chemical science》2021,12(2):675
Ligand-based mixed valent (MV) complexes of Al(iii) incorporating electron donating (ED) and electron withdrawing (EW) substituents on bis(imino)pyridine ligands (I2P) have been prepared. The MV states containing EW groups are both assigned as Class II/III, and those with ED functional groups are Class III and Class II/III in the (I2P−)(I2P2−)Al and [(I2P2−)(I2P3−)Al]2− charge states, respectively. No abrupt changes in delocalization are observed with ED and EW groups and from this we infer that ligand and metal valence p-orbitals are well-matched in energy and the absence of LMCT and MLCT bands supports the delocalized electronic structures. The MV ligand charge states (I2P−)(I2P2−)Al and [(I2P2−)(I2P3−)Al]2− show intervalence charge transfer (IVCT) transitions in the regions 6850–7740 and 7410–9780 cm−1, respectively. Alkali metal cations in solution had no effect on the IVCT bands of [(I2P2−)(I2P3−)Al]2− complexes containing –PhNMe2 or –PhF5 substituents. Minor localization of charge in [(I2P2−)(I2P3−)Al]2− was observed when –PhOMe substituents are included.Organo-aluminum mixed-valent complexes combine properties of both organic and transition element mixed-valent compounds. This supports delocalized electronic structures that are structurally and electronically tunable. 相似文献
24.
Nelson AG Bray TH Zhan W Haire RG Sayler TS Albrecht-Schmitt TE 《Inorganic chemistry》2008,47(11):4945-4951
In situ hydrothermal reduction of Np(VI) to Np(IV) in the presence of methylenediphosphonic acid (C1P2) results in the crystallization of Np[CH2(PO3)2](H2O)2 (NpC1P2-1). Similar reactions have been explored with U(VI) resulting in the isolation of the U(IV) diphosphonate U[CH2(PO3)2](H2O) (UC1P2-1), and the two U(VI) diphosphonates (UO2)2[CH2(PO3)2](H2O)3.H2O (UC1P2-2) and UO2[CH2(PO3H)2](H2O) (UC1P2-3). Single crystal diffraction studies of NpC1P2-1 reveal that it consists of eight-coordinate Np(IV) bound by diphosphonate anions and two coordinating water molecules to create a polar three-dimensional framework structure wherein the water molecules reside in channels. The structure of UC1P2-1 is similar to that of NpC1P2-1 in that it also adopts a three-dimensional structure. However, the U(IV) centers are seven-coordinate with only a single bound water molecule. UC1P2-2 and UC1P2-3 both contain U(VI). Nevertheless, their structures are quite distinct with UC1P2-2 being composed of corrugated layers containing UO 6 and UO 7 units bridged by C1P2; whereas, UC1P2-3 is found as a polar three-dimensional network structure containing only pentagonal bipyramidal U(VI). Fluorescence measurements on UC1P2-2 and UC1P2-3 exhibit emission from the uranyl moieties with classical vibronic fine-structure. 相似文献
25.
Titanium dioxide was deposited from aqueous suspension onto cellulosic surfaces.Titania was sourced from Degussa (P25TM,70:30 anatase:rutile).Dry uptake of particles was shown to be rapid and dominant with one-third of the deposition occurring in less than 30 s and over one-half in the first minute.Isotherms were recorded to compare the rate of titanium deposition on dry and pre-wetted cotton.In the dry case uptake reached a maximum in 30 min whereas in the pre-wetted case the uptake was seen to continue beyond 180 min.A broad trend of higher deposition occurring at lower pH was seen,corresponding to the region where surface charges were opposite and thus attractive.Dry pickup was less significant at high pH.The response to varying ionic strength was complex and was attributed to the combined effect of charge screening,particle aggregation and consequent particle entrapment or occlusion.Titania deposition into the interstices of woven cotton sheets resulted in the formation of inorganic,nanoparticulate skeletons which could be isolated by controlled combustion of the cellulose and thus cotton was suggested to have potential for the templated synthesis of high surface area semiconductor materials. 相似文献
26.
Gary S. Sayler Alice Layton Curtis Lajoie John Bowman Mike Tschantz James T. Fleming 《Applied biochemistry and biotechnology》1995,54(1-3):277-290
A variety of modern biotechnical approaches are available to assist in optimizing and controlling bioremediation processes.
These approaches are broad-ranging, and may include genetic engineering to improve biodegradative performance, maintenance
of the environment, and process monitoring and control. In addition to direct genetic engineering strategies, molecular diagnostic
and monitoring technology using DNA gene probing methods and new quantitative mRNA analytical procedures allows direct analysis
of degradative capacity, activity, and response underin situ conditions. Applications of these molecular approaches in process developments for trichloroethylene (TCE), polychlorinated
biphenyls (PCB), and polynuclear aromatic hydrocarbons (PAH) bio-oxidation in soils, aquifer sediments, and ground-water treatment
reactors have been demonstrated. Molecular genetic technologies permit not only the development of new processes for bioremediation,
but also new process monitoring, control strategies, and molecular optimization paradigms that take full advantage of vast
and diverse abilities of microorganisms to destroy problem chemicals. 相似文献
27.
T Madhusoodhanan Samit Mandal MP Sathyavathiamma Ramani NG Puttaswamy TS Mudhole A Mandal DK Avasthi R Shyam SK Datta 《Pramana》1999,53(3):541-544
The inclusive and exclusive measurements were carried out for 7Li projectile breakup on 27Al target at 48 MeV. In the inclusive data we have observed a broad peak around the beam velocity for alphas and tritons.
The exclusive data for alpha-triton coincidences show good agreement with the post-form DWBA theory of breakup reactions. 相似文献
28.
Ben-Itzhak I Wang PQ Xia JF Sayler AM Smith MA Carnes KD Esry BD 《Physical review letters》2005,95(7):073002
Laser-induced dissociation and ionization of H(+)(2) were simultaneously measured using coincidence 3D momentum imaging, allowing direct separation of the two processes, even where the fragment kinetic energy is the same for both processes. The results for 45 and 135 fs 790 nm pulses with an intensity of approximately 2.5 x 10(14) W/cm(2) differ from each other much more than one would expect from previous measurements with longer pulses. Ionization was negligible for the longer pulse and was strongly aligned along the laser polarization for the shorter pulse, but showed no structure in its kinetic energy distribution. In addition, the ionization to dissociation ratio was found to be much smaller than theoretically predicted for H(+)(2). 相似文献
29.
Precise, real-time, every-single-shot, carrier-envelope phase measurement of ultrashort laser pulses
In this Letter we demonstrate a method for real-time determination of the carrier-envelope phase of each and every single ultrashort laser pulse at kilohertz repetition rates. The technique expands upon the recent work of Wittmann and incorporates a stereographic above-threshold laser-induced ionization measurement and electronics optimized to produce a signal corresponding to the carrier-envelope phase within microseconds of the laser interaction, thereby facilitating data-tagging and feedback applications. We achieve a precision of 113 mrad (6.5°) over the entire 2π range. 相似文献