Collision energy spread (CES) generates a collision energy (CE) ramp around a collision energy center point, with the goal of providing a more, rich MS/MS spectrum of your analytes. The CE center point is either set in your acquisition method or computed on the fly using rolling collision energy (for peptide workflows).
When building your acquisition method you will specify an accumulation time for acquisition of the MS/MS spectrum and you will also specify a CES value. During acquisition, the accumulation time is divided into 10 steps and this the time spent on each point of the CES ramp. So if you set 50 msec accumulation time, each CE step will be 5 msec. Next, the total CE ramp width is computed ( CE Width = CE+CES – CE–CES ) and also divided into 10 steps. During MS/MS acquisition, sub-spectra are acquired at each CE (going from low CE to high CE) and summed into a single MS/MS spectrum which is saved to the datafile.
Note: it is important that you do not use accumulation times shorter than 20msec when using CES in your method.