page_title: Time-domain spectroscopy
hierarchical_section_title: Time-domain spectroscopy
caption_attribution_description: English: Addition of components of a broadened wave in time domain. Also shows frequency domain equivalent
context_page_description: Time-domain spectroscopy is a type of spectroscopy that measures the power of electromagnetic radiation as a function of time. Normal spectroscopy is frequency-domain spectroscopy. It measures radiation as a function of frequency or wavelength. Time-domain spectroscopy usually requires the use of Fourier transforms.
  Two monochromatic lights of different frequencies can combine to show interference patterns. At time t=0, the waves interfere constructively. This gives a maximum in the added plot. The waves get more out of phase. This leads to destructive interference and a minimum in the added plot. From one peak maximum to the next is a cycle. So when looking at two monochromatic lights, they can be graphed as two lines in the frequency-domain. The same two lights can be plotted as the sum of their waves in the time-domain.
  Absorptions in spectra usually look like broad peaks. This means that a peak may contain many wavelengths of radiation. These wavelengths can be plotted in the time domain. Notice that there are now smaller areas of constructive interference. This is because the closely spaced wavelengths quickly become more and more out of phase.
context_section_description: Time-domain spectroscopy is a type of spectroscopy that measures the power of electromagnetic radiation as a function of time. Normal spectroscopy is frequency-domain spectroscopy. It measures radiation as a function of frequency or wavelength. Time-domain spectroscopy usually requires the use of Fourier transforms.
  Two monochromatic lights of different frequencies can combine to show interference patterns. At time t=0, the waves interfere constructively. This gives a maximum in the added plot. The waves get more out of phase. This leads to destructive interference and a minimum in the added plot. From one peak maximum to the next is a cycle. So when looking at two monochromatic lights, they can be graphed as two lines in the frequency-domain (this plot shows power, P(ν), as a function of frequency). The same two lights can be plotted as the sum of their waves in the time-domain (this plot shows power, P(t), as a function of time).
  Absorptions in spectra usually look like broad peaks. This means that a peak may contain many wavelengths of radiation. These wavelengths can be plotted in the time domain. Notice that there are now smaller areas of constructive interference. This is because the closely spaced wavelengths quickly become more and more out of phase.
caption: Broad peaks in spectra are made of many wavelengths. These plots shows some of those wavelengths in the frequency and time domain.
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