We present SIMION 8.1 Monte Carlo type simulations of the response function and detection solid angle for long lived Auger states (lifetime τ ∼ 10(-9) - 10(-5) s) recorded by a hemispherical spectrograph with injection lens and position sensitive detector used for high resolution Auger spectroscopy of ion beams. Also included in these simulations for the first time are kinematic effects particular to Auger emission from fast moving projectile ions such as line broadening and solid angle limitations allowing for a more accurate and realistic line shape modeling. Our results are found to be in excellent agreement with measured electron line shapes of both long lived 1s2s2p(4)P and prompt Auger projectile states formed by electron capture in collisions of 25.3 MeV F(7+) with H2 and 12.0 MeV C(4+) with Ne recorded at 0° to the beam direction. These results are important for the accurate evaluation of the 1s2s2p (4)P/(2)P ratio of K-Auger cross sections whose observed non-statistical production by electron capture into He-like ions, recently a field of interesting interpretations, awaits further resolution.
Deep and fast electro-optic modulation is critical for high-speed near infrared signal processing. We combine the electro-absorption tunability of graphene with the high-Q resonance of a Bragg-based Fabry-Perot resonator at λ=1550 nm and show that ~100% free-space signal modulation (>50 dB extinction ratio, <1 dB insertion loss) at high speed (>1 GHz) can always be achieved independently of graphene quality (mobility), provided the device is operating in reflection mode and tuned in critical coupling with graphene. Remarkably, the critical coupling mechanism produces a higher extinction ratio for lower graphene mobility. We use practical considerations to optimize the device architecture and operation as a function of graphene mobility. With a small modification this scheme can be turned into a very sensitive acousto-absorption modulator with a ~30 dB/Å extinction ratio, or an index sensor with 10 7 %/RIU sensitivity. These designs can be easily extended throughout the midIR spectrum by appropriate scaling of layer thicknesses.
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