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The interactions of photons with matter are exploited in many ways. The most established scientific application based on these interactions is the fluorescence microscopy. In other applications, light is used to trigger chemical processes or the ablation of material. Similarly, lasers are used to cut materials (photodisruption).

When a beam of photons hits matter its energy may lead to the excitation of molecules. The photon beam must provide sufficient energy for the transition of electrons from the ground state to excitable states. Since the energy of photons depends on their frequency, short-wave light is a sufficiently strong energy source for the excitation of molecules (one-photon excitation).

On principle, it is impossible to cause the same excitation by adding the energies of two photons each representing half the necessary excitation energy (photons with twice the wavelength) (two-photon effect, Maria Göppert-Mayer, 1930). For two photons with half the necessary excitation energy to cause excitation, they must interact with the molecule close to simultaneously. While the probability for such an event is minute, it significantly increases at very high photon densities. The required high photon densities are technically generated by using femtosecond lasers (e.g. titanium-sapphire lasers) and by using lenses to focus the photon beam. The probability of a two-photon excitation drops rapidly with the distance from the laser's focus area. This limits the space where a two-photon excitation is likely to happen to the femto-liter range. Interestingly, this fact turns out to be advantageous for many applications:

Fluorescence Excitation (2-Photon Microscopy)
Triggered Photochemical Processes (2P Polymerization)
Photon-induced Cutting in Cells (2P Manipulation)

At the iba Institute in Heiligenstadt all three of the abovementioned 2P technologies for chemical and biological application are well established.

You find detailed information on the implementation of these 2P technologies on the respective pages.



2P-Techniken im iba Heiligenstadt
iba e.V. | Rosenhof | 37308 Heilbad Heiligenstadt | +49 (0) 3606 / 671 - 0 | iba(at)iba-heiligenstadt.de | typo3 hannover  microsoft crm add on