Displacementcalculator north south east west

Light Conversion’s compact Harpia system is able to to meet the diverse needs of ultrafast spectroscopy (Image: Nail Garejev)

Displacementcalculator with acceleration

Spectroscopy allows scientists to investigate pathways of energy flow between molecular states, the role of quantum effects in chemical reactions, and the time scales of relaxation processes within complex systems.

Waterdisplacementcalculator

It can cover a wide range of time scales, from femtoseconds to milliseconds, depending on the phenomena being studied, and the temporal resolution required to capture the relevant processes.

Other techniques are therefore necessary if higher temporal resolution is required for faster fluorescence events. Most of these methods are based on nonlinear optical cross-correlation between the fluorescence signal and a much shorter laser pulse. The fluorescence upconversion technique is based on a nonlinear optic method of sum-frequency generation, therefore its temporal resolution is equivalent to the laser pulse duration. A method that can achieve lower temporal resolution and is easier to implement is Kerr gating spectroscopy. In this technique, there is no need to scan wavelength by wavelength as the entire spectrum is captured at once. Fluorescence is good but only contains information about the excited states, whereas interesting things happen in the ground state as well. Therefore, we switch to time-resolved transient absorption spectroscopy.

Displacementcalculator with direction

Light Conversion has been a pioneer in this field for almost three decades and has recently brought in a complete commercial solution, called Harpia. With its various modules and customisation options, the Harpia spectroscopy system offers a compact and user-friendly solution to meet the diverse needs in the fascinating science of ultrafast spectroscopy.

Displacement of secondary reflection results from a small portion of the beam reflecting off the glass-air interface of the plate.

Transient absorption spectroscopy utilises short laser pulses that can be as short as tens of femtoseconds. These pulses can effectively ‘freeze’ the motion of molecules or materials at specific times during a reaction or a dynamic process. By varying the time delay between the pump and probe pulses, scientists can capture snapshots of the molecular system at various stages of its evolution, providing insights into the underlying dynamics. For this purpose, nanosecond or femtosecond transient absorption techniques can be used. The choice of spectroscopy technique depends on the specific research question, experimental requirements, and the timescales involved. Here are some of many reasons why femtosecond lasers are advantageous:

Enginedisplacementcalculator

Greta Bučytė, of Light Conversion's, shares the many advantages femtosecond lasers deliver to the field of ultrafast spectroscopy

Enginedisplacementcalculator cubic inches to liters

Beam Displacement is the displacement of a collimated beam incident on a tilted plane-parallel plate or window. This displacement occurs as a result of the beam travelling from one media to another media with a different refractive index. The change in refractive indices causes the beam to displace from its original path.

Molecular vibrations, electronic transitions, chemical reactions, energy transfer and fluorescence are all examples of processes that can be investigated using spectroscopy. Overall, it allows researchers to uncover the dynamic properties of molecules and materials across a broad range of time scales, aiding our understanding of fundamental processes in chemistry and physics, as well as material characterisation for solar cells or light-emitting diodes (LEDs).

Where ‘t’ is the thickness of the plate, ‘θ’  is the angle of incidence between beam and plate normal, and ‘n’  is the refractive index of the medium.

Several spectroscopic techniques are available to observe molecular processes. For instance, time-resolved fluorescence spectroscopy carries information on molecular processes in excited states, as well as their decay.​ There are a few time-resolved fluorescence spectroscopy techniques such as time-correlated single photon counting (TCSPC), fluorescence upconversion (FU), and Kerr gating. TCSPC enables fluorescence and phosphorescence lifetime measurements by measuring the arrival times of individual photons. TCSPC temporal resolution is limited by the detector response time in order of tens or hundreds of picoseconds, and the acquisition speed is determined by the repetition rate of the laser.

Femtosecond lasers and wavelength-tunable sources are the toolkits for ultrafast spectroscopy, providing high temporal resolution and a non-invasive nature to study material properties, as well as the ability to unravel complex phenomena and fundamental processes.