Three-pulse DEER/PELDOR pulse sequence. The sequence uses soft pulses computed with the Fokker-Planck formalism.
parameters.pulse_frq - frequencies for the three pulses, Hz parameters.pulse_pwr - power levels for the three pulses, rad/s parameters.pulse_dur - durations for the three pulses, seconds parameters.pulse_phi - initial phases for the three pulses, radians parameters.pulse_rnk - Fokker-Planck ranks for the three pulses parameters.p1_p3_gap - time between the first and the third pulses, seconds parameters.p2_nsteps - number of second pulse posi- tions in the interval between the first and the third pulse parameters.echo_time - time to sample around the ex- pected echo position parameters.echo_npts - number of points in the echo discretization parameters.rho0 - initial state parameters.coil - detection state parameters.method - soft puse propagation method, 'expv' for Krylov propagation, 'expm' for exponential propa- gation, 'evolution' for Spin- ach evolution function H - Hamiltonian matrix, received from context function R - relaxation superoperator, received from context function K - kinetics superoperator, received from context function
echo_stack - DEER echo stack, a matrix with p2_nsteps echoes with echo_npts points each
A number of complete examples for two- and three-electron systems are given in examples/esr_solids folder. A good way to proceed (soft_3_pulse_deer_2e.m example file) is to look at how the pulses affect the system:
then to inspect the echo stack as a function of the pump pulse position:
and finally to inspect the principal components of the echo stack. The most prominent component is the DEER trace, the other components come from the finite size of the spherical integration grid.
- For the method, start with 'expm', change to 'expv' if the calculation runs out of memory, and use 'evolution' as the last resort.
- Simulated echoes tend to be sharp and hard to catch because simulation does not have distributions in experimental parameters. Fourier transforming the echo prior to integration is recommended.
- The time in the DEER trace refers to the second pulse insertion point, after end of first pulse.
Version 2.4, authors: Ilya Kuprov