First observed in 1560, fluorescence has evolved into a powerful technique that enables entire fields of cutting-edge science and medicine. The only spectroscopic technique capable of resolving single molecules, fluorescence has moved from the lab to applications limited only by imagination.
The field of fluorescence is as diverse as it is beautiful. The sample under study may be liquid or solid, irregularly shaped, or accessible only outside the lab. A well-configured modular spectroscopy system can easily be reconfigured to study a wide range of samples in both the lab and the field.
Although fluorescence is sophisticated, it doesn’t need to be that complex. The beauty of modular spectroscopy is that you can invent as you go, trying different configurations until you find something that works. The tips and tricks below can help you get started. Or give us a call. It may just turn out that our team of application engineers have seen your application before. It’s not unusual, even if your application is.
Application: Making Good Fluorescence Measurements
- Sensitive: Concentrations as low as picomoles and femtomoles can routinely be detected, with even lower concentrations possible.
- Quantitative: Fluorescence signal is generally proportional to concentration. Fluorescence intensity responds to changes in concentration within picoseconds, making it well-suited for in-situ studies and monitoring fast processes.
- Safe: Unlike many other techniques for studying biological samples, it is non-destructive to the sample, and has no hazardous byproducts.
Other Common Applications
- Nature: analysis of gemstones, minerals, chlorophyll, and crude oil residues
- Forensics: detection of fingerprints & blood; analysis of fibers and other materials
- Phosphor thermometry: measurement of temperature using the lifetime or intensity ratios of fluorescence peaks
- Fundamental studies: use of laser-induced fluorescence to study the electronic structure of molecules and their interactions; concentrations in combustion, plasma, and flow phenomena
- Biology: detection of molecules, observation of cellular processes, and sorting cells
- Medical diagnostics: analysis of tissue for presence of cancer, glucose sensors, DNA sequencing, cytometry, and gel electrophoresis
What Is the Difference Between Quick View Mode and Relative Irradiance Mode?
Scope mode data shows the raw number of counts for each pixel in the array without any processing or correction for spectrometer sensitivity. This is important to remember, because each spectrometer has a different response function that comes from a combination of its individual elements and alignment. That can make scope mode misleading, showing a peak in the right general location, but with a distorted shape and/or center wavelength.
This can be corrected by calibrating against a blackbody light source of known color temperature and working in relative irradiance mode. A tungsten halogen lamp is a convenient standard, and works well for visible and NIR wavelengths. A relative irradiance measurement generates a corrected spectrum of relative intensity as a function of wavelength, scaled from 0 to 1 in arbitrary units.
Is relative irradiance mode always necessary for fluorescence measurements? No. Measurements taken with a single spectrometer are accurate relative to one another, even if the spectral shape is uncorrected. That means you can take the ratio of one fluorescence measurement to another and get an accurate change in the percent signal as a function of wavelength.
Relative irradiance is important when comparing measurements taken by different spectrometers, when determining the spectral shape, or when looking for peak location and shifts.
Featured Products for Fluorescence:
|USB4000-FL||Spectrometer is preconfigured for fluorescence measurements from 360 – 1100 nm. |
The spectrometer comes with a 200 µm slit and detector collection lens for increased light throughput.
|QE Pro-FL||Highly sensitive spectrometer specifically suited for low light-level applications such as fluorescence.|