Exposure mode of Spectral Aquisition

Exposure cycle is different from other continuous modes of acquisition. The key difference is that Exposure acquisition is carried in elapsed exposure time domain, rather than real time domain. Exposure mode is designed for photolytic studies where chemical reaction proceeds only in the presence of light and stops in the dark, such as cryogenic photolysis.

Structure

Each Exposure acquisition cycle starts with Shutter operation followed by data Integration sub-cycle. Unlike Flash-continuous mode, synchronization between Shutter operation and data acquisition is fixed in Exposure cycle in alternating order.

Time

Time dimension of acquired data and total duration of acquisition are defined in shutter elapsed time:  time progresses only when shutter is open. For each cycle, time calibration value equals elapsed shutter time at the end of last exposure. Data integration has no effect on time calibration and therefore can be set for as long as necessary. Exposure cycle can be paused without effect on time calibration of resulting data.

Acquisition will stop when elapsed exposure time for the latest cycle exceeds value specified by total duration. Like in other continuous modes, Exposure acquisition can run indefinitely if total duration is set to a negative value. 

Total real time duration of the acquisition, as well as date and time are saved in the document information header.

Parameters

Because real time has no meaning in Exposure cycle by definition, timing of data integration part is always static. Dynamic parameters, such as cycle factor, are not applied in Exposure cycles.  Thus, data integration in Exposure mode is equivalent to repeats of Single acquisition after each exposure.    

Timing of Shutter operation can be fully controlled in Exposure mode, including gradual change in exposure duration from cycle to cycle. Although Exposure acquisition cycle starts with Shutter operation, it can be suppressed for a specified number of initial cycles to allow for accumulation of reference (or dark) spectra.

Hardware

Exposure acquisition requires presence of Shutter controller.

Data flow

Processing, Destination, and Display options are identical to Continuous cycle.

Notes