Abstract: An apparatus for performing photochemical measurements on a liquid or liquid-containing sample includes a light generating system, an optical system configured for directing light from the light generating system towards the sample and a sensing system for measuring at least one optical property of the sample, wherein the light generating system is configured for generating light with intensity levels adjustable within a range, spanning at least three and preferably at least five orders of magnitude; and in that the optical system is configured for directing light from the light generating system towards the sample so as to generate a substantially uniform light intensity level, within a cylindrical region of the sample having a height larger than or equal to five time its radius.

Abstract: A method for detecting a reversibly photoswitchable chemical species in a sample, includes the steps of: a) illuminating the sample with light suitable to be absorbed by the chemical species triggering a reaction affecting an optical property of the chemical species, the first light being periodically-modulated at a fundamental modulation frequency; b) measuring the evolution of the optical property; c) extracting at least one of an in-phase component at a frequency which is an even multiple of the fundamental modulation frequency; and a quadrature component at a frequency which is an odd multiple of the fundamental modulation frequency of a signal representing the evolution; and d) using the extracted component or components for detecting the chemical species. An apparatus for carrying out the method is also provided.

Abstract: A method for detecting a photochemically active chemical species in a sample, comprising the steps of: a) illuminating the sample with light at a wavelength suitable to trigger a reaction affecting an optical property of the chemical species according to an illumination sequence, such that: in at least a first time window, the kinetics of the first reaction is limited by a photochemically-activated step of the reaction; and in at least a second time window, the kinetics of the first reaction is limited by a thermally-activated step; b) measuring the evolution of the optical property during the first and the second time windows; c) determining at least a first and a second time constant representing the kinetics of the first reaction in the first and the second time windows, respectively; and d) using the determined time constants for identifying the chemical species. An apparatus for carrying out such a method.

Abstract: A method is provided for detecting a fluorescent species that is reversibly photoswitchable at high frequency, and more precisely to a method for detecting at least one reversibly photoswitchable fluorescent species, including a step consisting in illuminating a sample containing a reversibly photoswitchable fluorescent species with a first illuminating light beam, of wavelength ?1, and periodically modulated at an angular frequency ?, and with a second illuminating light beam of wavelength ?2 different from ?1, which is periodically modulated at the angular frequency ?, the second illuminating light beam being modulated in antiphase with respect to the first illuminating light beam.

Abstract: A method is provided for detecting a fluorescent species that is reversibly photoswitchable at high frequency, and more precisely to a method for detecting at least one reversibly photoswitchable fluorescent species, including a step consisting in illuminating a sample containing a reversibly photoswitchable fluorescent species with a first illuminating light beam, of wavelength ?1, and periodically modulated at an angular frequency ?, and with a second illuminating light beam of wavelength ?2 different from ?1, which is periodically modulated at the angular frequency ?, the second illuminating light beam being modulated in antiphase with respect to the first illuminating light beam.

Abstract: A method for detection of at least one reversibly photo-convertible fluorescent species, comprises the following steps: a) illumination of a sample comprising said or at least one of the reversibly photo-convertible fluorescent species by a periodically modulated illuminating light; and b) detection of fluorescent emission emitted by the sample thus illuminated; wherein the method further comprises the following step: c) extraction of the amplitude of the intensity component of the fluorescent emission exhibiting the same periodicity as the periodically modulated illuminating light and a phase quadrature with respect to the same; and wherein the mean intensity of the illuminating light and the modulation frequency of the same are chosen to maximize the amplitude of the intensity component of the fluorescent emission.

Abstract: Method for detection of at least one reversibly photo-convertible fluorescent species (P), comprising the following steps: a) illumination of a sample comprising said or at least one of said reversibly photo-convertible fluorescent species by a periodically modulated illuminating light (FEX); and b) detection of fluorescent emission (FLU) emitted by the sample thus illuminated; characterized in that the method further comprises the following step: c) extraction of the amplitude (IFOUt) of the intensity component of said fluorescent emission exhibiting the same periodicity as said periodically modulated illuminating light and a phase quadrature with respect to the same; and in that the mean intensity of said illuminating light and the modulation frequency of the same are chosen in such a way as to maximise said amplitude of the intensity component of said fluorescent emission.

Abstract: The method according to the invention includes choosing a reaction presumed reaction mechanism; selecting, for said mechanism, at least one first function characteristic of a thermokinetic property that is invariant with the periodic variation frequency of a control parameter influencing said reaction, the first characteristic function being calculated at least from first-order oscillation amplitudes of the concentration of at least one of the species involved in said reaction. The method includes calculating a plurality of values of the first characteristic function from first-order oscillation amplitudes obtained experimentally and analyzing the calculated values of the first characteristic function to determine whether the first characteristic function is constant based on the calculated values, and if the first characteristic function is constant, assigning the presumed mechanism to said reaction.

Abstract: A method for determining the hydrodynamic radius for the constituents of an admixture, includes: (A) by separating capillary electrophoresis, the constituents of the admixture, leaving them within the capillary; (B) at one of the ends of the capillary obtained in this manner, containing, in different zones, the separated constituents, a detectable marker is injected in the region of a detection device which is placed at the side of the other end of the capillary; (C) a pressure difference is induced between the ends of the capillary in order to cause the various constituents separated in step (A) and finally the marker to migrate towards the outlet of the capillary; and (D) by analyzing the Taylor dispersion produced in step (C), the hydrodynamic radius is determined for each of the constituents, based on the detection time of the marker and the elution profile of each of the constituents.

Abstract: A method for determining the hydrodynamic radius for the constituents of an admixture, includes: (A) by separating capillary electrophoresis, the constituents of the admixture, leaving them within the capillary; (B) at one of the ends of the capillary obtained in this manner, containing, in different zones, the separated constituents, a detectable marker is injected in the region of a detection device which is placed at the side of the other end of the capillary; (C) a pressure difference is induced between the ends of the capillary in order to cause the various constituents separated in step (A) and finally the marker to migrate towards the outlet of the capillary; and (D) by analyzing the Taylor dispersion produced in step (C), the hydrodynamic radius is determined for each of the constituents, based on the detection time of the marker and the elution profile of each of the constituents.