The Stokes parameters (Sp, S1, S2, S3) of light are measured at an arbitrary wavelength over a wide wavelength range. The Stokes parameters S1 and S2 are easily obtained. But the Stokes parameter S3 at the arbitrary wavelength is affected by the phase difference error Δ1 of the quarter-wave plate mismatch and the Stokes parameters S1 or S2. Therefore, in this paper, S3 is obtained from both the intensity measurements by the circular polarizer rotating the quarter-wave plate by 0° and 90°. Then, S3 is obtained by considering only Δ1, but is not affected by S1 and S2. Also, though Δ1 is not accounted for, S3 is measured more accurately. 相似文献
Bis[2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato]cobalt(III) is proposed for the extraction and spectrophotometric determination of sulphated and sulphonated surfactants. The complex and the surfactants form ion-pairs which are extracted into benzene from O.1M hydrochloric acid. The absorbance of the benzene phase is measured at 560 nm against a reagent blank. Less than 25 mug of sodium di-(2-ethylhexyl) sulphosuccinate in 50-200 ml of sample solution is determined reproducibly by the proposed method. When applied to river water samples, the proposed method gives results which agree very well with those obtained by the standard Methylene Blue method. However, the proposed method is simpler and more sensitive than the Methylene Blue method. 相似文献
A combinatorial phage display method was applied to films composed of a stereoregular polymer of methacrylates. The phage clones with selective affinity for isotactic (it) poly(methyl methacrylate) (PMMA) were isolated. Greater amounts of the phage clones bound to it-PMMA, compared to other stereoregular PMMAs. The phage expressing ELWRPTR most strongly bound to the polymer, and the selectivity was also the best. The peptide motif essential for the specific interaction with the stereoregular polymer was revealed. 相似文献
Photoluminescence (PL) from purified (>90%) double-wall carbon nanotubes (DWNTs), which have been synthesized by zeolite catalyst-supported chemical vapor deposition (zeolite-CCVD), of very small diameters (0.8-nm average inner tube) is reported. The PL contour mappings for various ratios (1-90%) of double- versus single-wall carbon nanotubes by thermal oxidation have enabled us to unambiguously identify the chirality of inner tubes for the DWNTs synthesized. After the extensive high-temperature oxidation at 700 degrees C, high-purity (>90%) DWNTs of approximately 0.8 nm inner diameter are obtained, and most of these correspond to the DWNTs having inner tubes with chiralities of (7,5), (7,6), and (9,4). 相似文献
Within density functional theory with the general gradient approximation for the exchange and correlation, the bimetallic clusters AuPt and Au(6)Pt have been studied for their structure and reactivity. The bond strength of AuPt lies between those of Au(2) and Pt(2), and it is closer to that of Au(2). The Pt atom is the reactive center in both AuPt and AuPt(+) according to electronic structure analysis. AuPt(+) is more stable than AuPt. Au(6)Pt prefers electronic states with low multiplicity. The most stable conformation of Au(6)Pt is a singlet and has quasi-planar hexagonal frame with Pt lying at the hexagonal center. The doping of Pt in Au cluster enhances the chemical regioselectivity of the Au cluster. The Pt atom essentially serves as electron donor and the Au atoms bonded to the Pt atom acts as electron acceptor in Au(6)Pt. The lowest triplet of edge-capped rhombus Au(6)Pt clusters is readily accessible with very small singlet-triplet energy gap (0.32 eV). O(2) prefers to adsorb on Au and CO prefers to adsorb on Pt. O(2) and CO have stronger adsorption on AuPt than they do on Au(6)Pt. CO has a much stronger adsorption on AuPt bimetallic cluster than O(2) does. The adsorption of CO on Pt modifies the geometry of AuPt bimetallic clusters. 相似文献
Schließen und öffnen : N‐Boc‐N‐alkylsulfamide sind geeignete Substrate für die Titelreaktion. Die oxidative Cyclisierung im ersten Schritt ist hoch chemoselektiv sowie stereospezifisch und diastereoselektiv. Mit neuen Verfahren zur Öffnung der dabei erhaltenen Sechsringheterocyclen werden unterschiedlich geschützte 1,3‐Diamine zugänglich (siehe Schema).