Figure 1

(Color online) (a) STM current image of the Pt-deposited HOPG at 17 K ($129\times 129{\text{nm}}^2$, sample bias $V_s=-101\text{mV}$, tunneling current $I_t=157\text{pA}$). (b) Height-width distribution of the Pt clusters estimated from three different height images $\left(129\times 129{\text{nm}}^2\right)$ containing 586 Pt clusters that have been obtained at respective three different sample positions. The different colors represent the differences in the analyzed images. Both height and size do not show distinct values due to the resolution limit of the clusters in the large size images. The exact height and size values are obtained from high-resolution height images such as (d). (c) STM current image at 6.1 K ($8.4\times 8.4{\text{nm}}^2$, $V_s=249\text{mV}$, $I_t=205\text{pA}$). (d) STM height image at 6.1 K ($6.3\times 6.3{\text{nm}}^2$, $V_s=308\text{mV}$, $I_t=201\text{pA}$). (e) Line profile along $A{A}^{\prime }$ in the STM current image c, where $\sqrt{3}$ and $h$ represent the $\left(\sqrt{3}\times \sqrt{3}\right)R30°$ structure and the honeycomb structure, respectively. (f) Line profile along $B{B}^{\prime }$ line in the STM height image d, where $\beta$ represents the peak position difference of 0.246 nm.Reuse & Permissions

Figure 2

(Color online) (a) STS spectra of the Pt-deposited HOPG at 5.8 K (see text). (b) STM height image obtained during STS measurement ($3.1\times 3.9{\text{nm}}^2$, $V_s=305\text{mV}$, $I_t=117\text{pA}$). (c) Space-resolved STS spectra. (d)–(f) are the same series of the measurements as (a)–(c) obtained around a different Pt cluster on HOPG at 6.5 K ($0.6\times 0.5{\text{nm}}^2$, $V_s=303\text{mV}$, $I_t=132\text{pA}$). In all cases, ten STS spectra were measured and the averaged spectra are shown.Reuse & Permissions

Figure 3

(Color online) IETS spectra at 5.8 K obtained on the carbon atoms far from the Pt cluster (a), in the vicinity of the Pt cluster (b), and adjacent to the Pt cluster as indicated by the arrows in the STM height image $\left(V_s=291\text{mV},I_t=143\text{pA}\right)$. For comparison, the vibrational modes and plasmon peak energies (Ref. 32) are marked at the top of the figure. The phonon branches are specified as follows: out-of-plane acoustic (ZA), acoustic shear (SH), longitudinal acoustic (LA), out-of-plane optical (ZO), optical shear $\left({\text{SH}}^{\ast }\right)$, and longitudinal optical (LO).Reuse & Permissions

Figure 4

(Color online) (a) The schematic model of the calculated graphene sheet with a Pt cluster. (b) Calculated spatial distribution of the integrated local density of state from $E_f$ to $-0.2\text{eV}$ at different heights [the distribution above 0.053 nm and 0.233 nm are shown with red circles in (c) and (d)]. (e) Calculated total density of state of graphene and Pt/graphene, where the spectra are normalized by the each of the peak intensity for easy comparison. The Fermi energy for Pt/graphene has been shifted to $-0.1\text{eV}$ to obtain the same energy level at the bottom of the $s$ band between the results for graphene and for Pt/graphene.Reuse & Permissions