In the sample compartment of a conventional spectrophotometer, mounting of a polarizer before sample and an analyzer behind sample allows the determination of the optical rotatory dispersion of optical active media by...In the sample compartment of a conventional spectrophotometer, mounting of a polarizer before sample and an analyzer behind sample allows the determination of the optical rotatory dispersion of optical active media by measurement of the transmission ratio of crossed and parallel arranged polarizer and analyzer. A formula for the determination of the angle of rotation is derived from the transmission ratio. The arrangement is applied to determine the molar optical rotation of D-glucose in water in the wavelength range from 220 nm to 820 nm.展开更多
Laser pulse nonlinear transmission measurements through saturable absorbers of known absorption parameters allow the measurement of their energy density. On the other hand, nonlinear transmission measurements of laser...Laser pulse nonlinear transmission measurements through saturable absorbers of known absorption parameters allow the measurement of their energy density. On the other hand, nonlinear transmission measurements of laser pulses of known energy density through absorbing media allow their absorption parameter determination. The peak energy density w0P of second harmonic pulses of a mode-locked titanium sapphire laser at wavelength λP = 400 nm is determined by nonlinear energy transmission measurement TE through the dye ADS084BE (1,4-bis(9-ethyl-3-car-bazovinylene)-2-methoxy-5-(2’-ethyl-hexyloxy)-benzene) in tetrahydrofuran. TE(w0P) calibration curves are calculated for laser pulse peak energy density reading w0P from measured pulse energy transmissions TE. The ground-state absorption cross-section σP and the excited-state absorption cross-section σex at λP, and the number density N0 of the retinal Schiff base isoform RetA in pH 7.4 buffer of the blue-light adapted recombinant rhodopsin fragment of the histidine kinase rhodopsin HKR1 from Chlamydomonas reinhardtii were determined by picosecond titanium sapphire second harmonic laser pulse energy transmission measurement TE through RetA as a function of laser input peak energy density w0P. The complete absorption cross-section spectrum展开更多
The solubility of alloxazine in aqueous solution at pH 4 (10–4 molar HCl) and pH 10 (10–4 molar NaOH) at room temperature is determined by absorption spectroscopic characterization. Knowledge of the solubility is ne...The solubility of alloxazine in aqueous solution at pH 4 (10–4 molar HCl) and pH 10 (10–4 molar NaOH) at room temperature is determined by absorption spectroscopic characterization. Knowledge of the solubility is needed for sample preparation and quantitative spectroscopic solution characterization. Samples of different in-weight concentration were prepared and absorption spectra were measured versus storage time. The solubility limit concentration Csol was determined by the crossing point of the linearized absorption coefficient dependences on in-weight preparation concentration below and above the solubility limit. Values of Csol= 9.05 ± 1 μM and 14.5 ± 1 μM were determined for alloxazine in aqueous solution at pH 4 and pH 10, respectively.展开更多
文摘In the sample compartment of a conventional spectrophotometer, mounting of a polarizer before sample and an analyzer behind sample allows the determination of the optical rotatory dispersion of optical active media by measurement of the transmission ratio of crossed and parallel arranged polarizer and analyzer. A formula for the determination of the angle of rotation is derived from the transmission ratio. The arrangement is applied to determine the molar optical rotation of D-glucose in water in the wavelength range from 220 nm to 820 nm.
文摘Laser pulse nonlinear transmission measurements through saturable absorbers of known absorption parameters allow the measurement of their energy density. On the other hand, nonlinear transmission measurements of laser pulses of known energy density through absorbing media allow their absorption parameter determination. The peak energy density w0P of second harmonic pulses of a mode-locked titanium sapphire laser at wavelength λP = 400 nm is determined by nonlinear energy transmission measurement TE through the dye ADS084BE (1,4-bis(9-ethyl-3-car-bazovinylene)-2-methoxy-5-(2’-ethyl-hexyloxy)-benzene) in tetrahydrofuran. TE(w0P) calibration curves are calculated for laser pulse peak energy density reading w0P from measured pulse energy transmissions TE. The ground-state absorption cross-section σP and the excited-state absorption cross-section σex at λP, and the number density N0 of the retinal Schiff base isoform RetA in pH 7.4 buffer of the blue-light adapted recombinant rhodopsin fragment of the histidine kinase rhodopsin HKR1 from Chlamydomonas reinhardtii were determined by picosecond titanium sapphire second harmonic laser pulse energy transmission measurement TE through RetA as a function of laser input peak energy density w0P. The complete absorption cross-section spectrum
文摘The solubility of alloxazine in aqueous solution at pH 4 (10–4 molar HCl) and pH 10 (10–4 molar NaOH) at room temperature is determined by absorption spectroscopic characterization. Knowledge of the solubility is needed for sample preparation and quantitative spectroscopic solution characterization. Samples of different in-weight concentration were prepared and absorption spectra were measured versus storage time. The solubility limit concentration Csol was determined by the crossing point of the linearized absorption coefficient dependences on in-weight preparation concentration below and above the solubility limit. Values of Csol= 9.05 ± 1 μM and 14.5 ± 1 μM were determined for alloxazine in aqueous solution at pH 4 and pH 10, respectively.
