Local bonding states of ion-irradiated graphite characterized by photon-stimulated desorption (PSD) spectroscopy

We investigated the local bonding states of D2+-irradiated graphite using a photon-stimulated ion-desorption (PSID) technique, which incorporates polarized near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The carbon K-edge NEXAFS conducted in Auger electron yield mode showed no significant dependence on polarization angles (θ), while H+- and D+-PSID NEXAFS showed polarization-dependent resonances. The σ*(C-H) resonance in H+ ions and σ*(C-D) in D+ ions showed enhanced yields, which were larger at θ = 10 deg. than at θ = 45 deg. and the σ*(C=C) peak in D+ ions showed a prominent enhancement which was stronger at θ = 10 deg. than at θ = 45 deg.. Our results are interpreted assuming that the difference in local structures between C-H and C-D bonds is reflected in the PSID NEXAFS