Digital pulse programmer for an electron-spin-resonance computer-controlled pulsed spectrometer

Abstract

A computer‐controlled pulsed electron‐spin‐resonance spectrometer(EPR) based on a 100‐MHz pulse programmer directly interfaced to a DEC LSI‐11/23 minicomputer has been constructed. The pulse programmer is a programmable digital signal generator capable of generating parallel binary data patterns and complex digital timing waveforms to directly form the time base for pulsed EPR experiments. It utilizes an emitter coupled logic (ECL) design and provides eight channels of simultaneous ECL and TTL outputs; 16 state periods programmable between 20 ns and 655.36 μs per period with a resolution of 10 ns; an internal hardware autoincrement counter for one state period duration; two internal loop counters; and 2‐byte TTL parallel interface to the LSI‐11/23. All timed intervals are derived from and are synchronous to the 100‐MHz master clock. The spectrometer configuration, analogous to modern commercial FT‐NMR spectrometers, permit direct programming of pulsed EPR experiments using software developed on the host computer to operate the pulse programmer.