UV- Laserfluorimeter

Over the last decade, our team developed different versions of transportable UV-Laserfluorimeter with fibre optical probe for environmental and process analysis.

As light source a frequency up-converted diode pumped Nd:YAG-laser with a short pulsed emission at 266 nm is applied. The wavelength is perfect for excitation of mono- (BTXE) and polycyclic aromatic hydrocarbons (PAH), as well as humic substances, aromatic aminoacids and proteins.

Deploying optical waveguides out of quartz, the laser pulse is flexible guided to the measurement place for fluorescence excitation and the emission is than back-guided to the detection unit. Due to the special geometry of the fibres in the probe the fluorescence emission is efficiently collected and the entry of directed stray light minimized. The detection was implemented in different ways:

Time-dependent sequential, lifetime-resolved detection:

The fluorescence emission is spectrally fragmented and the spectra are detected at different times after the excitation pulse is emitted with a gated, intensified CCD-Camera. Out of the obtained data the spectrometer-software build-up an emission-decay-spectrum.

Wavelength-dependent sequential, lifetime-resolved detection:

In applying a monochromator, a single emission wavelength can be chosen for which a high temporal resolved fluorescence decay curve can be detected. This is possible in deploying a time-correlated single photon counting technique. Out of several decay curves the software builds- up an emission-decay-spectrum.

Integral fluorescence detection:

In combination with a diode-line or CCD-line spectrometer a fluorescence emission spectra can be obtained. This setup is used if the fluorescence decay times in the application are shorter as the decay of the instrument response function.

The control of all system versions is implemented with a self-developed spectrometer software. Furthermore with this software a qualitative and quantitative data evaluation is feasible that ranges from simple linear one-component-regression over decay-time analysis to complex multi-component-analysis by deploying chemometric methods.

For feasibility studies the laserfluorimeters are placed at interested party’s disposal.

Further information:

F. Lewitzka, M. Niederkrüger, G. Marowsky, „Application of Two-Dimensional LIF for the Analysis of Aromatic Molecules in water”, in P. Hering, J.P. Lay, S. Strey (Editors): „Laser in Environmental and Life Sciences”, 141-161, Springer Verlag, Berlin, 2003.

P. Karlitschek, F. Lewitzka, U. Bünting, M. Niederkrüger, G. Marowsky, „Detection of aromatic pollutants in the environment using UV-laser-induced fluorescence“, Appl. Phys. B 67, 497-504, 1998.

UV-Laserfluorimeter

Sponsorship:

DBU funding „Entwicklung eines Laserfluorimeters zum Nachweis von organischen Schadstoffen in Wasser“ (1994-1996, Grand No. 01989)

BMBF support program Mikrosystemtechnik „BTXE und PAK Sensor“ (1996-1999, Grand No. 16SV558/0)

BMBF support program Mikrosystemtechnik „BTXE und PAK Sensor II“ (1999-2003, Grand No. 16SV1112/5)