A pulse train comprising chirped pulses of electromagnetic energy can be used to excite a sample, such as for spectroscopic analysis. The respective chirped pulses can include a frequency sweep across a first specified bandwidth during a respective chirped pulse duration, the respective chirped pulse duration establishing a first frequency-domain comb peak separation. A width of a frequency-domain comb peak can be established at least in part by a total duration of the pulse train, and a bandwidth of the first frequency-domain comb can be determined at least in part by the first specified bandwidth of the frequency sweep of the respective chirped pulses.