For time-resolved spectroscopy of non-reproducible experiments (e.g. many chemical reactions) the above mentioned Step Scan approach is not applicable anymore. However, also for this class of experiments time-resolved data can be obtained using the so-called Rapid Scan technique. In this case the interferometer mirror moves very fast and up to 4 spectra can be extracted from each full forward-backward interferometer scan.
Since the duration of one scan does not only depend on the mirror velocity but also on the distance, the achievable number of spectra per second also depends on spectral resolution. Equipped with the Rapid Scan option, already the VERTEX 70v and the INVENIO are able to achieve more than 70 spectra per second. Moreover the VERTEX 80/80v based on the innovative UltraScanTM interferometer sets the standards, achieving more than 110 spectra per second!
The interleaved time-resolved (TRS) acquisition mode for INVENIO and VERTEX series spectrometers is a powerful approach for time-resolved measurements of a certain class of repetitive experiments with extraordinary signal to noise ratio. The interferometer mirror is moving continuously and the zero-crossings of the internal HeNe laser are used to trigger the experiment. Data are not only acquired at the HeNe zero crossings (t=0) but also at mirror positions in between, belonging to certain time delays Δt. Hence the system continuously acquires data and in principle a full series of time-resolved interferograms can be collected within one single scan. Interleaved time-resolved FTIR spectroscopy is exclusively offered by Bruker.