Time-Resolved Instrumentation

Starting January 2008 ISS offers both - time-domain and frequency-domain instrumentation!

ISS has over 20 years of experience in producing time-resolved instrumentation. To learn more about the basics of time-resolved measurements we refer you to our technical note: Fluorescence Lifetime.

• Time-Domain Instruments from ISS

• Frequency-Domain Instruments from ISS

What are the main characteristics of Frequency Domain (FD)?

• In FD fluorescence lifetime is calculated from 2 measurable parameters: phase angle and modulation
• FD is in general a faster, easier and less artifact-prone measurement
• FD requires no deconvolution with an instrument response function (IRF)
• FD allows direct, one step measurements of anisotropy decays (rotational correlation times)
• FD is better in resolving short lifetime contributions as compared to TD
• In FD cross-correlation detection results in increased signal-to-noise ratios and rejection of undesired harmonics
• FD is the method of choice for lifetime-based sensing and real-time measurements because of high sampling rates in the millisecond time scale

What are the main characteristics of Time Domain (TD)?

• As compared to FD, TD is a more direct way of measuring lifetime
• Unlike FD, TD requires no reference but measurement of an instrument response function (IRF)
• TD anisotropy decay measurements do require two separate measurements at each plane of polarization
• TD has a low duty cycle - approximately only one photon per every 50 flashes is measured
• TD is the preferred method for measuring low fluorescence compounds