Characterization of high-quality NTCDA films on metal substrates

Vibrational properties of the compressed and the relaxed 1,4,5,8-naphthalene-tetracarboxylic dianhydride monolayer on Ag(111)

“…11,14 However, in our experiments these recipes did not prove reliable and produced heterogeneous results, depending on deposition rate and sample temperature during NTCDA deposition. For example, residual 3D-clusters formed upon annealing may remain unnoticed by SPA-LEED or using electron spectroscopy due to their small areal coverage, while they are readily detected by IRAS.…”

“…[10][11][12] Internal multipole moments represent another important lateral interaction mechanism of large organic molecules; NTCDA and PTCDA, for example, display pronounced quadrupole moments and lateral ordering as well as 2D-island growth have been associated with this specific property. 11,13 NTCDA adsorption on Ag(111) has been investigated with several experimental methods such as spot profile analysis low-energy electron diffraction (SPA-LEED), [10][11][12] temperature programmed desorption (TPD), 10 STM, 10, 12 XPS, 11, 14-17 ultraviolet photoemission spectroscopy (UPS), 14,17 NEXAFS, 11,[14][15][16][17][18][19] and normal incidence x-ray standing wave (NIXSW). 20,21 In the 1-2 monolayer (ML) range these studies provided valuable information concerning lateral order, 10, 12 molecular orientation and distortion, 14,15,18 chemical bonding, 11,17,20 and vertical distances.…”

“…NEXAFS studies show that the molecules from the NTCDA monolayer on Ag(111) are oriented with their molecular plane parallel to the surface with a tilt angle of less than 5 • (this estimate also holds for the NTCDA bilayer). 14,15 The present study focuses on monolayers of NTCDA on Ag(111) and, for the first time, their detailed examination using infrared absorption spectroscopy (IRAS). The application of vibrational spectroscopy represents a powerful tool to characterize organic (mono)layers on metal and semiconductor surfaces.…”

“…The system NTCDA/Ag(111) therefore represents an ideal model system to demonstrate and analyze the multitude of features in such spectra and also to provide independent and complementary information to support or disprove conclusions based on the established electron spectroscopies alone. [14][15][16][17][18][19][20][21] …”

Electronic structure of 1ML NTCDA/Ag(111) studied by photoemission spectroscopy

“…Especially when the coverage is larger than one monolayer, the molecules tend to be oriented perpendicular and form a densely packed structure similar to the one of NTCDA single crystals [17]. Note, however, that in the multilayer regime, not discussed in this paper, the molecular orientation depends strongly on the substrate temperature during deposition; only at temperatures below 200 K, a uniform molecular orientation with the molecular plane parallel to the substrate can be obtained [11,18]. XPS has been applied to investigate the electronic properties and the interaction between molecule and substrate.…”