Color centers in diamonds have shown excellent potential for applications in quantum information processing, photonics, and biology. Here we report chemical vapor deposition (CVD) growth of nanocrystalline diamond (NCD) films as thin as 5-6 nm with photoluminescence (PL) from silicon-vacancy (SiV) centers at 739 nm. Instead of conventional 4-6 nm detonation nanodiamonds (DNDs), we prepared and employed hydrogenated 2 nm DNDs (zeta potential = +36 mV) to form extremely dense (∼1.3 × 10 cm), thin (2 ± 1 nm), and smooth (RMS roughness < 0.8 nm) nucleation layers on an Si/SiO substrate, which enabled the CVD growth of such ultrathin NCD films in two different and complementary microwave (MW) CVD systems: (i) focused MW plasma with an ellipsoidal cavity resonator and (ii) pulsed MW plasma with a linear antenna arrangement. Analytical ultracentrifuge, infrared and Raman spectroscopies, atomic force microscopy, and scanning electron microscopy are used for detailed characterization of the 2 nm H-DNDs and the nucleation layer as well as the ultrathin NCD films. We also demonstrate on/off switching of the SiV center PL in the NCD films thinner than 10 nm, which is achieved by changing their surface chemistry.

In this report we present XPS data for five amino acids (AAs) (tryptophan, methionine, glutamine, glutamic acid, and arginine) with different side chain groups measured in solid state (powder form). The theoretically and experimentally obtained chemical structure of AAs are compared. Here, we analyse and discuss C 1 s, N 1 s, O 1s and S 2p core level binding energies, FWHMs, atomic concentrations of the functional groups in AAs. The experimentally obtained and theoretically calculated ratio of atomic concentrations are compared. The zwitterionic nature of methionine and glutamine in solid state was determined from protonated amino groups in N 1s peak and deprotonated carboxylic groups in the C 1s spectrum. The obtained XPS results for AAs well correspond with previously reported data.

Understanding materials with dimensions down to few nanometers is of major importance for fundamental science as well as prospective applications. Structural transformation and phononconfinement effects in the nanodiamonds (NDs) have been theoretically predicted below 3 nm size. Here we investigate the effect of size on the surface chemistry, microscopic structure, and Raman scattering of high-pressure high-temperature (HPHT) and detonation nanodiamonds (DNDs) down to 2-3 nm. The surface and size of NDs are controlled by annealing in air and ultracentrifugation resulting in three ND fractions. Particle size distribution (PSD) of the fractions is analyzed by combining dynamic light scattering (DLS), analytical ultracentrifugation (AUC), small angle X-ray scattering (SAXS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) as complementary techniques. Based on the obtained PSD we identify size-dependent and synthesis-dependent differences of NDs properties. In particular, interpretation of Raman scattering on NDs is revisited. Comprehensive comparison of detonation 3 and pure monocrystalline HPHT NDs reveals effects of diamond core size and defects, chemical and temperature (in)stability as well as limitations of current phonon confinement models. In addition, low-frequency Raman scattering in the 20 -200 cm -1 range is experimentally observed.The size dependence of this signal for both HPHT NDs and DNDs suggests that it may correspond to confined acoustic vibrational, "breathing-like" modes of NDs.

Ultrafast singlet exciton fission in thin solid films after UV laser photoexcitation was observed using transient absorption spectroscopy.

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New building units (unimers) for metallo-supramolecular polymers 2,5-bis(2,2':6',2''-terpyridine-4'-yl)thiophene, M, and 5,5'-bis(2,2':6',2''-terpyridine-4'-yl)(2,2'-bithiophene), B, with ionic groups attached to thiophene rings are prepared by the modification of corresponding bromo-precursors and assembled with Zn(2+) and Fe(2+) ions into alcohol-soluble conjugated constitutional-dynamic polyelectrolytes (polyelectrolyte dynamers). Ionization of side groups only slightly affects the absorption spectra of unimers as well as dynamers but dramatically changes their solubility. Cyclic conformations of unimer molecules resulting from intramolecular interactions between tpy end-groups and cationic or polar (-CH2Br) side groups are proposed to explain the spectral conformity of the M- and B-type unimers and their dynamers and also inhibition of the ionization reaction with tpy end-groups. The absorption spectra and excitation profiles of Raman spectra show that mainly the red arm of the metal-to-ligand charge transfer band of Fe-dynamers is significantly contributed with transitions involving thiophene rings. The constitutional dynamics of Zn-dynamers is fast while that of Fe-dynamers is so slow that it allows effective separation of the dynamer to fractions in SEC columns. Electronic spectra and viscosity measurements proved that excess of Fe(2+) ions results in shortening of the dynamer chains and their end-capping by these ions.

Contrary to the planktonic state of bacteria, their biofilm form represents severe complications in areas such as human medicine or food industry due to the increasing resistance against harsh conditions and treatment. In the present study, infrared attenuated total reflection (IR-ATR) spectroscopy has been applied as an analytic tool studying Escherichia coli ( E. coli) biofilm formation close to real time. We report on IR spectroscopic investigations on the biofilm formation via ATR waveguides probing the biofilm in the spectral window of 1800–900 cm−1 at dynamic flow conditions, which facilitated monitoring the growth dynamics during several days. Key IR bands are in the range 1700–1590 cm−1 (amide I), 1580–1490 cm−1 (amide II), and 1141–1006 cm−1 extracellular polymeric substances (EPS), which were evaluated as a function of time. Cyclic fluctuations of the amide I and amide II bands and a continuous increase of the EPS band were related to the starvation of bottom-layered bacteria caused by the nutrient gradient. Potential death of bacteria may then result in cannibalistic behavior known for E. coli colonies. Observing this behavior via IR spectroscopy allows revealing these cyclical changes in bottom-layered bacteria within the biofilm under continuous nutrient flow, in molecular detail, and during extended periods for the first time.

Well-defined covalent surface functionalization of diamond is a crucial, yet non-trivial, matter because of diamonds intrinsic chemical inertness and stability. Herein, we demonstrate a twostep functionalization approach for H-terminated boron-doped diamond thin films, which can lead to significant advances in the field of diamond hybrid photovoltaics. Primary diamond surface functionalization is performed via electrochemical diazonium grafting of in situ diazotized 4-iodoaniline. The freshly grafted iodophenyl functional moieties are then employed to couple a layer of thiophene molecules to the diamond surface via two wellestablished Pd-catalyzed cross-coupling reactions, i.e. Stille and Sonogashira. X-ray photoelectron spectroscopy analysis indicates a dense coverage and successful cross-coupling in both cases. However, we find that the Stille reaction is generally accompanied with severe surface contamination, in spite of process optimization and thorough rinsing. Sonogashira cross-coupling on the other hand provides a clean, high quality functionalization over a broad range of reaction conditions. The protocols employing Sonogashira reactions thus appear to be the method of choice toward future fabrication of high-performance dye-functionalized diamond electrodes for photovoltaic applications.