Bea Botka

• PhD in Applied Physics
• Research Associate at Hungarian Academy of Sciences

By exposing flat and curved carbon surfaces to coronene, a variety of van der Waals hybrid heterostructures are prepared, including coronene encapsulated in carbon nanotubes, and coronene and dicoronylene adsorbed on nanotubes or graphite via π-π interactions. The structure of the final product is determined by the temperature of the experiment and...

Coronene was encapsulated in single-walled carbon nanotubes (SWNT) by vapor-phase filling at high (450 °C) and low (385 °C) temperature and by nanoextraction from supercritical carbon dioxide. The presence of coronene inside the tubes was demonstrated indirectly via the formation of double-walled nanotubes (DWNT). To this end several subsequent ann...

We report the development of a detection optics for the integration of Raman scattering and scanning probe microscopy at low temperature based on a parabolic mirror. In our set-up half of the paraboloid mirror covers a solid angle of $\pi$ corresponding to a numerical aperture of N.A.\,$\approx 0.85$. The optical system can be used for far- and nea...

We report the preparation and characterization of hybrid materials from conducting polymers and single walled carbon nanotubes. Electrochemical polymerization yields nanotubes wrapped by conducting polymers – polyaniline, polycarbazole and melanin (i.e., polydopamine). The materials were characterized by ultraviolet–visible–near infrared, infrared,...

Treatment of carbon nanotubes by oxidizing acids is extensively used to dissolve metal residues from raw nanotube samples. The effect of acid treatment on the tubes themselves is twofold: it introduces uniform carboxylic sidegroups on the tube ends and defects, and it increases the overall charge concentration on the nanotube walls, thereby p-dopin...

Single-wall carbon nanotubes (SWCNTs) have extraordinary electronic and optical properties that depend strongly on their exact chiral structure and their interaction with their inner and outer environment. The fluorescence (PL) of semiconducting SWCNTs, for instance, will shift depending on the molecules with which the SWCNT’s hollow core is filled...

Growing graphene nanoribbons from small organic molecules encapsulated in carbon nanotubes can result in products with uniform width and chirality. We propose a method based on encapsulation of 1,2,4-trichlorobenzene from the liquid phase and subsequent annealing. This procedure results in graphene nanoribbons several tens of nanometers long. The p...

Surface passivation is one of the commonly used approaches to reduce the density of defects on the surfaces and interfaces hindering the performance and stability of perovskite optoelectronic devices. Although surface passivation leads to performance improvement for the targeted devices, details of the complex intermolecular interactions occurring...

Graphene nanoribbons are prepared inside boron nitride nanotubes by liquid phase encapsulation and subsequent annealing of 1,2,4‐trichlorobenzene. The product is imaged with high resolution transmission electron microscopy, and characterized by optical absorption and Raman spectroscopy. Carbon‐containing material is detected inside the boron nitrid...

Graphene nanoribbons are prepared inside boron nitride nanotubes by liquid phase encapsulation and subsequent annealing of 1,2,4-trichlorobenzene. The product is imaged with high resolution transmission electron microscopy, and characterized by optical absorption and Raman spectroscopy. Carbon-containing material is detected inside the boron nitrid...

Growing graphene nanoribbons from small organic molecules encapsulated in carbon nanotubes can result in products with uniform width and chirality. We propose a method based on encapsulation of 1,2,4-trichlorobenzene, from the liquid phase, and subsequent annealing. This procedure results in 6-armchair graphene nanoribbon without byproducts. The pr...

The unusually chiral-structure-dependent properties of single-wall carbon nanotubes (SWCNTs) are also strongly influenced by their internal and external environment, which can therefore be investigated through optical spectroscopy.[1,2] In order to study this influence in detail, we developed a hyperspectral IR fluorescence imaging setup based on a...

Hybrid materials based on carbon nanotubes continue to attract considerable interest due to the broad variety of both the cages outside and the encapsulated species inside. This review focuses on organic molecules as guests in single-walled carbon nanotube hosts. The majority of results presented here have been attained in recent years by various m...

Specific and tunable modification to the optical properties of single-wall carbon nanotubes (SWCNTs) is demonstrated through direct encapsulation into the nanotube interior of guest molecules with widely varying static dielectric constants. Filled through simple ingestion of the guest molecule, each SWCNT population is demonstrated to display a rob...

Potassium addition to mixed‐halide perovskites was found to be a promising way to overcome their major stability issue, the segregation of the mixed phase to iodide and bromide‐rich regions. To fully exploit the potential of potassium addition, it is essential to achieve a better understanding of its working mechanism, and understand the limitation...

Successful encapsulation of sexithiophene (6T) molecules by two different methods is presented: sublimation filling at 400°C and nanoextraction from supercritical carbon dioxide (sc‐CO2) at 50°C. Differences in the Raman spectra of the two samples indicate thermally induced polymerization during sublimation filling, increasing the electronic conjug...

Adsorption of carboxymethyl cellulose (CMC) in aqueous solution onto a titania nanoparticle film has been studied using in situ attenuated total reflectance infrared spectroscopy (ATR-IR). CMC was adsorbed onto the positively charged titania surface in neutral, partially charged, and fully charged state. The response of the adsorbed polyelectrolyte...

The optical properties of single-wall carbon nanotubes (SWCNTs) are extremely sensitive to their external and internal environment. For example, filling the endohedral cavity with water molecules results in characteristic shifts and broadening of both the SWCNTs’ radial breathing mode vibrational frequency and their optical (electronic) transitions...

Specific and tunable modification to the optical properties of single-wall carbon nanotubes is demonstrated through the direct encapsulation into the nanotube interior of guest molecules with measured static dielectric constants. Optical measurements on SWCNT populations containing over thirty distinct simple compounds of varying static dielectric...

We report the development of a detection optics for the integration of Raman scattering and scanning probe microscopy at low temperature based on a parabolic mirror. In our set-up half of the paraboloid mirror covers a solid angle of $\pi$ corresponding to a numerical aperture of N.A.\,$\approx 0.85$. The optical system can be used for far- and nea...

Individual molecules filled into carbon nanotubes exhibit Raman activity but very weak, if any, infrared absorption. We will present infrared (transmission and ATR), Raman and transmission electron microscopy data of various filled nanotubes (sorted by diameter and metallicity; encapsulating organometallic, aromatic and fullerene-based molecules) t...

Non-covalent functionalization of carbon nanotubes (CNTs) by polymers or aromatic systems is a rapidly emerging field. Its importance originates in the possibility of combining special (optical, electric, or dispersive) properties of the added molecules with the mechanical stability of nanotubes. A special application is to use the polymers as inte...

Transparent conducting films are rapidly emerging as one of the most promising applications of carbon nanotubes. In these less-than-perfect materials, understanding the types of defects and their effect on the transport and optical properties plays a significant role. In this contribution, we present examples of these effects, both beneficial and a...

We followed the preparation of double-walled carbon nanotubes (DWNTs) from fullerene peapods by optical and Raman spectroscopy in a systematic way. 1.4 nm average diameter nanotubes were opened by oxidation in air, and filled with C60 by sublimation. The peapods were converted to DWNTs by annealing at 1250 °C. As a reference, a control sample was a...

For carbon nanotubes filled with fullerenes (“peapods”), it is a key issue to find an analytical method that distinguishes the molecules inside the nanotube from those adsorbed on its surface. High-resolution transmission electron microscopy (HRTEM) detects both encapsulated and adsorbed molecules which are large enough (e.g., fullerenes), but bein...

We present infrared and Raman spectra of carbon nanotubes (CNT's) coated by the conducting polymers polyaniline (PANI), polycarbazole (PCz) and melanin (polydopamine). These hybrid materials have been prepared by electrochemical polymerization and exhibit increased conductivity and enhanced electron transfer from the electrolyte to the electrode. I...