A stop flow spectrometer is an analytical instrument designed specifically for studying rapid reaction kinetics. Its core is to achieve instantaneous mixing and stop flow of reactants, and to monitor the reaction process in real time through optical signals. The following provides a detailed explanation of the working principle and advantages:

1、 Working principle

1. Rapid mixing system: The stop flow spectrometer drives the reactants (such as reagents A and B) to mix at high speed in the mixing chamber through dual injectors or pneumatic devices, and the mixing time can be as short as 0.5 milliseconds. The mixing method includes injection or pressure drive to ensure that the reaction is initiated under homogeneous conditions.

2. Optical detection system: The mixed solution flows into an observation cell (usually 20-25 μ L), and the optical system emits light of a specific wavelength through a light source (such as a xenon lamp or mercury xenon lamp). After screening by a monochromator, the sample is irradiated. Detectors (such as photodiodes or CCDs) can record real-time changes in absorbance, fluorescence, or scattering signals with a time resolution of microseconds (10 μ s-10ms).

3. Time resolved control: Trigger synchronous mixing and optical detection, continuously recording the signal change curve with time after the reaction stops flowing, in order to derive kinetic parameters such as reaction rate constant and activation energy.

2、 Advantages

1. High time resolution: capable of capturing reaction processes ranging from milliseconds to microseconds, revealing transient intermediates and rapid reaction mechanisms.

2. High sensitivity: capable of detecting extremely small changes in light signals, suitable for low concentration samples or weak signal reactions.

3. Flexibility: Supports multiple optical detection modes (absorption, fluorescence, scattering, etc.), and can adjust wavelength (200-900nm), time window (logarithmic/linear distribution), and mixing ratio to meet different experimental needs.

4. Precise and controllable: The mixing delay time (20ms-600s) and flow rate are fully automatically controlled by software, and the experiment has strong repeatability; The temperature control system (-20 ° C to 80 ° C) maintains stable reaction conditions.

5. Automated operation: Integrated data acquisition and processing system, automatically records signal curves and deducts baselines to reduce human errors.

6. Wide applicability: It can be used in various fields such as chemical synthesis, protein ligand binding, electron transfer, etc., especially suitable for analyzing intermolecular interactions and reaction driving forces.