Increasing sensitivity of pulse EPR experiments using echo train detection schemes

Modulation depth enhancement of ESEEM experiments using pulse trains

“…Note that this addition of echoes in our experiments would be practically different than the detection schemes proposed in [23] because in our case the pulse train is the method itself and not only its detection component. Nevertheless, both approaches lead to SNR gain.…”

“…The method presented here could be combined with the idea of multiple echo detection during a train of refocusing π pulses for increasing the signal/noise ratio (SNR), as was recently shown for a variety of pulse EPR experiments [23]. This would include the addition of all (or selected) relevant refocused echoes for a given train of N pulses, provided that the corresponding ESEEM spectra are not distorted.…”

“…Surprisingly, the echo modulations due to the weakly coupled nuclei were significantly enhanced with the number of applied pulses, N . Although the CPMG sequence is a well-established NMR method [17,18] and has been recently used in EPR spectroscopy either as a dynamical decoupling method [19,20,21] or as a detection scheme to increase the signal-to-noise ratio in pulse EPR experiments [22,23], to date its relation to the ESEEM effect has been reported in some cases [24,25] but a systematic analysis is still lacking. Herein we analyze our previous observation by extending our study to a two-dimensional (2D) method where the repeated part of the sequence is based on the refocusing primary echo method [4].…”

Direct Spectroscopic Detection of ATP Turnover Reveals Mechanistic Divergence of ABC Exporters

“…ENDOR measurements were performed on a home-built W-band (94.9 GHz) spectrometer (Goldfarb et al, 2008; Mentink-Vigier et al, 2013) at a temperature of 10 K; for all the experiments the magnetic field was set at the center of the |m S , m I > = |−1/2, −3/2> ➔ |+1/2, −3/2> line (second peak of the 55 Mn ( I = 5/2) hyperfine sextet) at 3.374 T (ν L ( 1 H) = 143.65 MHz). The standard Davies ENDOR sequence π mw – T – t RF – T – π/2 mw – τ – π mw – τ – echo (Davies, 1974) was used, in which the echo intensity is monitored as a function of the RF (radio frequency).…”

“…The T delay, added in order to prevent overlap between the ring-down phenomena following the pulses, was set to T = 1 μs; the delay for the Hahn echo generation sequence was set to τ = 1 μs. The pulse sequence was supplemented with echo train acquisition in order to increase the sensitivity (Mentink-Vigier et al, 2013). …”