Structure, function and reaction kinetics of macromolecules in chemical biology*
Ultrafast fluorescence upconversion spectroscopy system
Fluorescence Upconversion Spectroscopy
In terms of temporal resolution, measurement sensitivity and accuracy, fluorescence upconversion is ultimately the most competitive technology.
The technique has been used to study the ultraviolet, visible and near-infrared spectral regions and has been used to study many different phenomena such as solvation kinetics, intramolecular coherence vibrations, ultrafast photoisomerization reaction kinetics, charge transfer reactions, fluorescence properties of DNA nucleosides and nucleotides, solvation reactions at multiple sites in globular proteins, as well as water kinetics in biological recognition, and condensed matter.
The ultrafast fluorescence upconversion spectroscopy system is a detection system for transient fluorescence spectroscopy and dynamics with femtosecond time-resolved scales constructed in combination with a femtosecond laser light source. The operating principle is shown in the figure on the right. First, the femtosecond laser light source is split into two beams, one beam is used to excite the sample, and the generated fluorescence is collected and converged into a linear crystal with the second femtosecond laser (gated pulsed laser) to generate a sum frequency signal. The delay time between the two laser beams is controlled by the optical delay line, and the sum frequency signal at different delay times reflects the fluorescence intensity at that moment, thus realizing the acquisition of fluorescence decay signal at the femtosecond scale.