Noncontact AFM and differential reflectance spectroscopy joint analyses of bis-pyrenyl thin films on bulk insulators: Relationship between structural and optical properties

Nony, Laurent; Para, Franck; Luangprasert, Philipda; Naubron, Jean-Valère; Loppacher, Christian; Leoni, Thomas; Thomas, Alain; Ranguis, Alain; D’Aléo, Anthony; Fagès, Frédéric; Becker, Conrad

doi:10.1103/physrevb.97.235434

Cited by 3 publications

(7 citation statements)

References 97 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although the choice of gaussian functions is not optimal to fit the DR spectra [60], this approach makes the DRS/absorption in solvent benchmarking self-consistent. Therefore, the DR spectra have been fitted accordingly (cf.…”

Section: Drs On Kcl(001)mentioning

confidence: 99%

“…The analysis of the DR spectra permits to extract the dielectric function of the adsorbed layers, as well [60]. But here again, the use of a metallic substrate is challenging.…”

mentioning

confidence: 99%

“…Indeed, as detailed in ref. [60], the non-linear nature of Fresnel equations makes the interpretation of the DR spectra tedious. Assuming the imaginary part of the dielectric function of the substrate as a constant greatly simplifies the approach, which is not the case with metals whose absorption in the UV-vis range is much structured [61,62].…”

mentioning

confidence: 99%

See 2 more Smart Citations

Stereoisomeric selection upon adsorption: A structural and optical study of curcuminoid derivatives on ultrathin films of KCl on Au(111) and on bulk KCl(001)

et al. 2021

Self Cite

View full text Add to dashboard Cite

We present a combined Scanning Tunneling Microscopy (STM), non-contact Atomic Force Microscopy (nc-AFM) and Differential Reflectance Spectroscopy (DRS) study aiming at the characterization of the relationship between structural and optical properties of a supramolecular assembly of a curcuminoid derivative adsorbed on two kinds of substrates: bilayers of KCl on Au (111) (2 ML KCl/Au(111)) and KCl(001) bulk. The molecule features a difluoroboron (-BF 2 ) complex as well as cyano (-CN) end groups, which induces an internal dipole moment of a few Debyes. The comparative study of the structural properties of the molecules adsorbed on 2 ML KCl/Au(111), which allows for STM characterization, and KCl bulk, which allows for nc-AFM and DRS characterization, shows that the molecular adsorption is similar on both substrates. STM and nc-AFM give evidence that the on-surface condensation of the molecules into supramolecular assemblies is steered by two main interactions: the molecule-substrate interaction between the -CN end groups of the molecule and the cationic K + species, as well as an in-plane intermolecular interaction involving -BF 2 and phenyl groups. Based on Density Functional Theory calculations, we propose an epitaxial molecular structure described by a two-molecules unit cell forming a 8 × 2 supercell on the KCl surface that grows in form of ribbons along the < 100 > or < 010 > directions of the substrate, which are polar. Among several possible stereo-isomers for the molecule, it is found that the balance between vertical and in-plane interactions selects the one whose size matches the distance between K + species to condense on the substrate and not the most stable one stemming from the gas phase. Finally, optical spectroscopy in solvent and DRS measurements performed on the supramolecular assembly exhibit similar features identified as three absorption peaks tracing a π → π * electronic transition followed by a vibronic progression, plus a broader band featuring a set of higher energy transitions. Due to both, the weak electrostatic interactions and a lack of π − π interactions in the condensed molecular phase, DR spectra exhibit no major excitonic effect, but a non-rigid redshift of the molecular absorption band compared to the situation in solvent. This observation is found to be consistent with the isomer selection due to the transition from the gas phase to the on-surface condensed phase.

show abstract

Section: Drs On Kcl(001)mentioning

confidence: 99%

“…The analysis of the DR spectra permits to extract the dielectric function of the adsorbed layers, as well [60]. But here again, the use of a metallic substrate is challenging.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Stereoisomeric selection upon adsorption: A structural and optical study of curcuminoid derivatives on ultrathin films of KCl on Au(111) and on bulk KCl(001)

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…In many cases, molecule-metal interactions can adversely affect the intrinsic electronic characteristics of molecular adsorbates and quench the optical properties [9][10][11][12][13]. Consequently, recent studies aiming to characterize the relation of adsorption, supramolecular organization, and electronic and optical properties in organic layers relied on bulk insulator supports [14][15][16]. As a promising alternative to bulk insulators, ultrathin dielectric films can act as decoupling layers but maintain the possibility to perform STM and STS measurements [17].…”

Section: Introductionmentioning

confidence: 99%

“…On two-dimensional materials, pyrene serves as an anchor for noncovalent functionalization, e.g., to develop graphene platforms to be used in sensing applications [ 65 – 67 ] and to employ h BN monolayers for capturing aromatic organic pollutants [ 68 ]. On bulk insulators, it was, for instance, demonstrated how the optical properties of an adsorbed bispyrene derivative relate to the structural order of the assemblies [ 15 ].…”

Section: Introductionmentioning

confidence: 99%

Self-assembly and spectroscopic fingerprints of photoactive pyrenyl tectons on hBN/Cu(111)

Zimmermann¹,

Seufert²,

Đorđević³

et al. 2020

Beilstein J. Nanotechnol.

View full text Add to dashboard Cite

The controlled modification of electronic and photophysical properties of polycyclic aromatic hydrocarbons by chemical functionalization, adsorption on solid supports, and supramolecular organization is the key to optimize the application of these compounds in (opto)electronic devices. Here, we present a multimethod study comprehensively characterizing a family of pyridin-4-ylethynyl-functionalized pyrene derivatives in different environments. UV–vis measurements in toluene solutions revealed absorption at wavelengths consistent with density functional theory (DFT) calculations, while emission experiments showed a high fluorescence quantum yield. Scanning tunneling microscopy (STM) and spectroscopy (STS) measurements of the pyrene derivatives adsorbed on a Cu(111)-supported hexagonal boron nitride (hBN) decoupling layer provided access to spatially and energetically resolved molecular electronic states. We demonstrate that the pyrene electronic gap is reduced with an increasing number of substituents. Furthermore, we discuss the influence of template-induced gating and supramolecular organization on the energies of distinct molecular orbitals. The selection of the number and positioning of the pyridyl termini in tetrasubstituted, trans- and cis-like-disubstituted derivatives governed the self-assembly of the pyrenyl core on the nanostructured hBN support, affording dense-packed arrays and intricate porous networks featuring a kagome lattice.

show abstract

A practical and effective method for reducing differential reflectance spectroscopy noise

2022

Nanotechnology and Precision Engineering

View full text Add to dashboard Cite

Differential reflectance spectroscopy (DRS) is a powerful tool to study processes during thin-film growth, especially that of transition metal dichalcogenides and organic thin films. To satisfy the requirements for in situ and real-time monitoring of film growth, including spectral resolution and sensitivity at the level of monolayers and even sub-monolayers, the most challenging technical task in DRS is to reduce noise to an extremely low level so that the best possible signal-to-noise ratio can be achieved. In this paper, we present a simplified and cost-effective DRS apparatus, with which we show that the measurement noise is mainly composed of thermal drift noise and explore the temperature-dependence of the DRS signal. Based on the results obtained, we propose an easily realized and effective scheme aiming to reduce the noise. Experimental results demonstrate that this scheme is effective in stabilizing reliable signals for a long period of several hours. Significant noise reduction is achieved, with the typical average noise of the DRS system being decreased to 0.5‰ over several hours. The improved DRS system is applied to study the growth of an organic semiconductor layer for an organic field-effect transistor device. The results indicate that the apparatus proposed in this paper has potential applications in fabrication of devices on the nanoscale and even the sub-nanoscale.

show abstract

Noncontact AFM and differential reflectance spectroscopy joint analyses of bis-pyrenyl thin films on bulk insulators: Relationship between structural and optical properties

Cited by 3 publications

References 97 publications

Stereoisomeric selection upon adsorption: A structural and optical study of curcuminoid derivatives on ultrathin films of KCl on Au(111) and on bulk KCl(001)

Stereoisomeric selection upon adsorption: A structural and optical study of curcuminoid derivatives on ultrathin films of KCl on Au(111) and on bulk KCl(001)

Self-assembly and spectroscopic fingerprints of photoactive pyrenyl tectons on hBN/Cu(111)

A practical and effective method for reducing differential reflectance spectroscopy noise

Contact Info

Product

Resources

About