Structure and electronic structure of van der Waals interfaces at a Au(1 1 1) surface covered with a well-ordered molecular layer of n-alkanes

Enhanced Rashba Splitting of Au(111) Surface States with Hydrogen‐Bonded Melamine‐Based Organic Framework

“…In adsorption systems of other organic molecules, a modified SS was clearly observed as long as the organic molecular thin film grew epitaxially. [22][23][24] However, as discussed previously for the LEED data, the MHC exhibited epitaxial growth on Au(111); thus, it is unlikely that translational symmetry disorder was the reason for the low intensity. Therefore, this reduction in the photoemission intensity is not a general phenomenon but may be unique to MHC/ Au(111).…”

“…These values agree well with those reported in previous works. [22,56] As shown in Figure 7c,d, MHC/Au(111), that is, the SS of Au(111), was significantly modified. The results in Figure 7c,d are discussed in detail later in the paper; here, we present three characteristic points.…”

“…This value is smaller than those of NTCDA/Au(111) (ΔE 0 NTCDA = 166 meV) and PTCDA/Au(111) (ΔE 0 PTCDA = 164 meV), which are weak chemisorption systems of π-conjugated molecules, and TTC/ Au(111) (ΔE 0 TTC = 145 meV) and Xe/Au(111) (ΔE 0 Xe = 146 meV), which are considered typical physical adsorption systems. [20,[22][23][24] According to the results of this comparison, the ΔE 0 MHC is the smallest and MHC/Au(111) can be interpreted as an ideal physisorption system. However, the Δk || and Δa R values of MHC/ Au(111) are significantly larger than those of NTCDA/Au(111) (Δk || NTCDA = 0.007 Å −1 ; Δa R NTCDA = 0.04 eV Å), [24] PTCDA/Au(111) (Δk || PTCDA = 0.006 Å −1 ; Δa R PTCDA = 0.03 eV Å), [24] TTC/Au(111) (Δk || TTC = 0.002 ± 0.001 Å −1 ; Δa R TTC = 0.067 ± 0.015 eV Å), [23] and Xe/Au(111) (Δk || Xe = 0.009 Å −1 ; Δa R TTC = 0.098 ± 0.017 eV Å).…”

“…For example, when Xe or the n-alkane molecule tetratetracontane (TTC) is adsorbed on Au(111), the adsorption structure is well-defined, and the modified SS is clearly observed, but no clear band folding has been reported. [20,22,23] However, when 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), which are typical n-type organic semiconductors, are adsorbed on Au(111), strong band folding is observed, as in the case of MHC/Au(111). [24] A common feature of these molecules is that they contain elements with higher electronegativity than carbon, such as nitrogen and oxygen.…”

“…[15][16][17][18] On the other hand, the adsorption of noble gases or organic molecules on a noble metal (111) changes the strength of Rashba coupling. [19][20][21][22][23][24][25] This is interesting given that the Rashba coupling is determined by the asymmetry of the wave function of the surface electrons in a very narrow region no less than 1 Å from the nucleus of the outermost layer of the metal surface, where molecules adsorbed at least a few angstroms away from the nucleus can affect the Rashba coupling.…”