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Surface enhanced Raman spectroscopy of fullerene C 60 drop-deposited on the silvered porous silicon


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Surface enhanced Raman spectroscopy (SERS) of fullerene C60 drop-deposited from the 1.410⁻⁴ M aqueous solutions on the silvered porous silicon (Ag/PS) is reported for the first time. The used concentration is found to be not detected by the ordinary Raman spectroscopy. It is shown that SERS-spectrum of the fullerene deposited from the air-aged solution are characterized by less intensity than that of the fullerene solution kept out of the air. This indicates degradation of the fullerene solution due to oxidation. The results are prospective for the fast qualitative and quantitative analysis of the fullerene-based materials.
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Journal of Physics: Conference Series
Surface enhanced Raman spectroscopy of fullerene C60 drop-deposited
on the silvered porous silicon
To cite this article: N Khinevich et al 2017 J. Phys.: Conf. Ser. 917 062052
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IOP Conf. Series: Journal of Physics: Conf. Series 917 (2017) 062052 doi :10.1088/1742-6596/917/6/062052
Surface enhanced Raman spectroscopy of fullerene C60
drop-deposited on the silvered porous silicon
N Khinevich1, K Girel1, H Bandarenka1, V Salo2, A Mosunov2
1Belarusian State University of Informatics and Radioelectronics, Minsk, 220013,
Republic of Belarus
2Sevastopol State University, Sevastopol, 299053, Russian Federation
Abstract. Surface enhanced Raman spectroscopy (SERS) of fullerene C60 drop-deposited
f-4 M aqueous solutions on the silvered porous silicon (Ag/PS) is reported for
the first time. The used concentration is found to be not detected by the ordinary Raman
spectroscopy. It is shown that SERS-spectrum of the fullerene deposited from the air-aged
solution are characterized by less intensity than that of the fullerene solution kept out of the
air. This indicates degradation of the fullerene solution due to oxidation. The results are
prospective for the fast qualitative and quantitative analysis of the fullerene-based
60707684 molecules are called fullerenes. In
these molecules, atoms of carbon are located at the vertices of regular hexagons or pentagons that
cover the surface of sphere or spheroid. C60 occupies special position among all the fullerenes. This
molecule demonstrates the highest symmetry and, as a consequence, the greatest stability.
Fullerenes are characterized by a number of unique properties including high sorption capacity,
photoconductivity, mechanical strength, low surface energy, biocompatibility, etc. Thorough study
              
storage, catalytic systems, micro- and nanoelectronics and biomedicine [1]. Accurate qualitative
and quantitative analysis of the fullerenes is an urgent task to realize their successful application.
Considering biomedicine, this problem has to be overcome at very low concentrations to control
fullerene transfer through biological membranes, accumulation in proteins or cells and interaction
with other submicron bioorganic objects. Scanning tunneling microscopy, nuclear magnetic
resonance spectroscopy, different methods of vibrational spectroscopy have been used to study the
fullerenes [2]. Since the beginning of fullerene discovery its Raman frequencies have been
calculated [3] and measured [2]. Theoretical analysis [4] showed that 46 fundamental modes can be
       60 molecular vibrations. Two of these modes are
characterized by Ag symmetry, one Au, three 1g, four 1u, five 2u, six Gg, six Gu, eight
g and seven u  1u symmetry are active during registration of the
gg symmetries are active in Raman spectroscopy, while
the other t           
Raman spectroscopy comparing to other techniques is in possibility to realize SERS effect. This
means enormous enhancement of the Raman intensity by study of analyte adsorbed on the
nanostructured metallic surfaces that are usually called SERS substrates. SERS spectroscopy
allows to detect and investigate trace amounts of substances and thus is very attractive for the study
of fullerenes. Several approaches of registration of C60 SERS spectrum in nonaqueous Ag and Au
colloidal systems have been already developed [5, 6]. These methods provide good sensitivity,
Saint Petersburg OPEN 2017 IOP Publishing
IOP Conf. Series: Journal of Physics: Conf. Series 917 (2017) 062052 doi :10.1088/1742-6596/917/6/062052
however, the solvent media contributes to the resulting Raman spectrum. That is why it requires to
make additional manipulations to see only the Raman spectra of fullerenes. In this work, we
propose to solve such a problem by using SERS substrate based on porous silicon (PS). PS covered
with metallic nanostructures can be used as an effective SERS substrate [7]. In this work, we were
able to register intensified Raman scattering of the C60 fullerene thanks to the SERS substrate
composed of silver nanoparticles on PS (Ag/PS). According to our knowledge, such results have
not been previously published.
Fabrication of SERS substrates based on PS consists of two major steps: formation of porous
template and deposition of metallic nanostructures on its surface. PS was fabricated by an
electrochemical anodization of n+-type silicon wafer in electrolyte of HF, deionized H2O and
C3H7OH mixed in the volume ratio 1:3:1. Prior to anodization process silicon wafer was cleaned in
a solution NH4OH, H2O2 and H2O mixed in a volume ratio of 1:1:4. To remove native oxide from
silic                  
average pore diameter is 60 nm. Silver nanostructures were formed on PS by a chemical deposition
from aqueous solution of AgNO3. Deposition process was carry out at room temperature. Before
applying of analyte SERS-substrates were rinsed in HCl aqueous solution to remove contaminants
which adsorbed on the surface of the substrates from environment. Fullerenes C60 were drop-
deposited on the Ag/PS substrate from the air-age    
          -4 M. SERS-spectra of
fullerene were recorded with the 3D scanning confocal microscope Confotec NR500 using 633 nm
laser and signal accumulation time 1 s. The laser spot varied in the 500 nm range while power of
laser beam coming from the microscope objective was about 0.68 mW.
Results and discussion
Combinations of PS morphologies and regimes of metal deposition give rise to create the metallic
nanostructures with fascinating SERS characteristics. In this work we used regimes of Ag/PS
samples formation favourable for the most effective SERS according to [7]. SERS substrates
presented silver nanostructures on the external surface of PS with an average size of silver
nanoparticles in the range varying from 50 to 300 nm. Figure 1 shows SEM images of the virgin
Ag/PS samples and those after drop deposition of the fullerene C60 at different magnifications. It is
well-seen that the analyte is non-uniformly distributed on the Ag/PS surface (Fig. 1, b). Figure 1, f
presents enlarged top view of the fullerene-coated Ag/PS. Following this image fullerene molecules
formed the fullerite crystals with dimensions of 150 360 nm that are coalesced in aggregates of
of fullerene C60 drop-deposited on the SERS substrates. Measurements of the ordinary Raman
spectra of fullerene deposited on the glass plate, samples of the silicon wafer and Ag-free PS were
impossible due to low concentration of the carbon nanostructures. Both spectra in Figure 2 have
three prominent bands of fullerene C60 such as Hg(1), Ag(1) and Ag(2) [8]. The last one has the
highest intensity and 
mode is caused by the symmetry breaking of the fullerene molecule. For instance, this can be
observed at the molecule polymerization. Linear polymerization is accompanied by the Ag(2) shift
1 1 is usually connected with formation of
C60 dimer or C60O2 [10]. The Ag(2) band of the kept of air fullerene is most intensive near the 1466
cm1 while the maximum of the same band of the air-aged sample is shifted to the 1464 cm1
position indicating the stronger oxidation of the last one. Both samples have a left shoulder in the
Ag(2) band extending to 14591460 cm1 which shows a presence of a small amount of the
polymerized fullerene molecules. This occurs due to C60 photopolymerization at the natural light.
The bands Hg(1) and Ag(1) of the air-aged sample are slightly red-shifted. The kept out of the air
sample is also characterized by weak bands Hg(2) Hg(8) typical for fullerene C60 [8]. The marked
bands in the SERS spectra correspond to ten vibrational modes of fullerene C60 (Ag, Hg ) which are
Saint Petersburg OPEN 2017 IOP Publishing
IOP Conf. Series: Journal of Physics: Conf. Series 917 (2017) 062052 doi :10.1088/1742-6596/917/6/062052
Raman-active [4]. SERS intensity of the air-aged sample is about four orders of magnitude lower
than that of the other sample. These results are caused by the changes in the fullerene structure due
to oxidation of the air-aged sample and its destruction.
Figure 1. SEM images of the Ag/PS substrates (a, c, e) before and (b, d, f) after C60 deposition.
Saint Petersburg OPEN 2017 IOP Publishing
IOP Conf. Series: Journal of Physics: Conf. Series 917 (2017) 062052 doi :10.1088/1742-6596/917/6/062052
Figure 2. SERS-spectra of fullerene C60 deposited on Ag/PS from (a) kept out of air and (b) air-
aged solutions.
We showed that Ag/PS can be used as effective SERS substrates for the detection and study of the
structure of the submolar concentration of the fullerene C60 aqueous solutions. Structural changes
of the air-aged fullerenes in comparison with the kept out of the air samples were revealed. The
both fullerene samples were photopolymerized. At the same time, the air-aged sample was much
more oxidized in comparison with the kept of the air fullerene solution. The obtained results open
new opportunities for the precise control of the fullerene properties in different materials.
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... The other commercial product (BelSERS substrates [ nology/sers-active-substrates-for-increasing-sensitivity-of-raman-spec troscopy] that is based on the silvered meso-or macro-PS have demonstrated its applicability for detection of peptides [143] and proteins [134], meldonium [171], DNA [148], phospholipids [142], fullerenes [172] and other organic molecules [36,103,105]. ...
Surface-enhanced Raman scattering (SERS) spectroscopy is one of the most prospective methods combining state-of-the-art nanomaterials and optical techniques for highly sensitive express-analysis and detection of organic and bioorganic objects in liquids and gases. Special programs have been recently started all over the world to bring the SERS-spectroscopy closer to wide implementation in medical diagnostics, forensics, security, monitoring sanitary conditions, etc. Despite outstanding features of SERS-spectroscopy, its effective practical use has been particularly slowed down by moderate reproducibility, non-versatility, and restrictions imposed by commercially available SERS-active substrates to measurement and storage regimes. The present review reports SERS-active substrates constituted by noble metals' nanoparticles (NPs) and porous silicon (PS), which potentially can be a tool to overcome the above-mentioned limitations. The PS template acts as a highly ordered host nanomaterial for the formation of a variety of metallic nanostructures, which morphological and optical properties can be easily tuned for the best performance to meet the customer requirements via managing PS synthesis regimes. An indubitable advantage of PS is the compatibility of its fabrication process with basic microelectronics operations and micro-electromechanical systems (MEMS) that make it possible to integrate SERS-active areas in a silicon chip. In contrast to the previously published reviews in the field, this one covers the most recent results on formation, characterization, and application of PS-based substrates demonstrating prominent SERS-activity that have been achieved for the last decade including modifications with graphene or Bragg structures, detection of molecules at amount down to attomolar concentration, bacteria recognition, etc.
... The integrated electronic structure of graphene sheet can be altered by doping in it [45][46][47] and the doped graphenes show improvement in detecting molecules [48][49][50]. Similarly several potent researches have established effective roles of other nanoclusters like fullerene [51,52], helicene [53,54] and CNTs [55,56]. In recent years, Surface Enhanced Raman Spectra (SERS) studies of a number of biologically active molecules and the efficiency of the nanoclusters as drug delivery systems have been reported [57][58][59][60][61][62][63][64][65]. ...
The nanocluster-based drug delivery system is of much importance, now days. This manuscript studies the interaction of pristine / substituted / doped GQDs, fullerene, helicene and CNT with bempedoic acid, which is an effective alternative of statins in the treatment of hypercholesteremia. The adsorption energies are calculated at B3LYP-D3/6-311G+(2d,p) level in order to study the adsorption of bempedoic acid over the surfaces of the nanoclusters incorporating Grimme’s dispersion correction. Surface enhanced Raman scattering (SERS), which is a sound approach to vibrational spectroscopy, is used in order to detect bempedoic acid. All the studies signify that bempedoic acid can be detected with these nanoclusters and the negative adsorption energies advocate for the possible use of these nanoclusters as effective drug delivery system in case of bempedoic acid. Adsorption energy of bempedoic acid over helicene was found to be the most negative among the mentioned nanocluster systems, while adsorption on the surface of CNT was found to be the least negative.
... In this work we primarily concentrate on the shifts at 270 cm −1 , 495 cm −1 , and 1468 cm −1 . Peaks obtained with 784 nm laser excitation shown in Figure 7 are in agreement with the fundamental vibrational modes associated with the symmetry groups Hg, Ag1, and Ag2 found in the literature [37]. Figure 7 also indicates that the spectral region that undergoes enhancement is relative to the distance between the mirrors. ...
Full-text available
Raman spectroscopy is a widely used characterization technique in material science. It is a non-destructive tool with relatively simple instrumentation, and provides intrinsic qualitative information of analytes by probing their vibrational modes. In many cases, Raman enhancement is essential for detecting low-intensity signals in high-noise environments, spectrally unresolved features, and hidden modes. Here we present optical and Raman spectroscopic characterization of fullerene C 60 in a gold microcavity. The fabrication of single-layered gold mirrors is facile, low cost and direct but was proven to give considerably significant enhancement. The findings of this work demonstrate the cavity resonance as a powerful tool in obtaining tunability over individual peak for selective enhancement in the tuned spectral range. The PL of the material within the cavity has demonstrated a red shift assumed to be caused by the low-energy transitions. These transitions are induced by virtual low-energy states generated by the cavity. We further observe that adopting this principle enables resolution of active Raman modes that until now were unobserved. Finally, we assigned the new experimentally observed modes to the corresponding motions calculated by DFT.
Full-text available
Plasmonic nanostructures demonstrating an activity in the surface-enhanced Raman scattering (SERS) spectroscopy have been fabricated by an immersion deposition of silver nanoparticles from silver salt solution on mesoporous silicon (meso-PS). The SERS signal intensity has been found to follow the periodical repacking of the silver nanoparticles, which grow according to the Volmer-Weber mechanism. The ratio of silver salt concentration and immersion time substantially manages the SERS intensity. It has been established that optimal conditions of nanostructured silver layers formation for a maximal Raman enhancement can be chosen taking into account a special parameter called effective time: a product of the silver salt concentration on the immersion deposition time. The detection limit for porphyrin molecules CuTMPyP4 adsorbed on the silvered PS has been evaluated as 10(-11) M.
Full-text available
Photoinduced polymerization and photoinduced diffusion of molecular oxygen in thin C60 films irradiated by femtosecond laser pulses are investigated. A comparison of the Raman scattering and absorbed energy spectra and the irradiation doses required to observe photopolymerization using continuous-wave radiation and femtosecond pulses shows that the efficiency of both photoinduced processes decreases considerably in the latter case.
Fullerene chemistry has become a very active research field, largely because of the uniqueness of the C60 molecule and the variety of fullerene derivatives that appear to be possible. Chemists have learned how to generate a diverse group of fullerene derivatives, where molecular fragments are bonded to the C60cage, leaving the cage essentially intact, although the C-C bond lengths in the vicinity of the attachment are perturbed. Many of these chemical reactions have taken advantage of the electrophilic properties of fullerenes, that is, their tendency to attract electrons. Because all the carbon bonds in the fullerene molecule are satisfied within the molecular shell, substitution reactions involving the exchange of one chemical group for another, as is common in organic chemistry, are not possible, although substitution of boron for carbon in the shell has been observed in molecular beam experiments. Furthermore, catastrophic decomposition of the carbon shell occurs in oxygen above 400ºC.
We recently demonstrated that C60 and C70, as well as other fullerenes, can be deposited and accumulated on surfaces using laser ablation of graphite in an Inert gas atmosphere. After learning of the work of Krätschmer et al. indicating the presence of C60 in carbon soot, we showed that samples consisting almost exclusively of C60 and C70 can be sublimed from such soot. Vibrational Raman spectra of C60 and C70 were obtained from these samples. The C60 spectrum Is consistent with the calculated spectrum of Buckmlnsterfullerene, and the strongest three lines can be assigned on the basis of frequency and polarization. The NMR spectrum of dissolved C60 was then obtained, and found to consist of a single resonance, establishing the icosahedral symmetry of this molecule. STM images of the C60 molecules on a Au(111) crystal face show that these clusters form hexagonal arrays with an intercluster spacing of 11.0 Å and are mobile at ambient temperature. Distinctly taller species evident in the arrays are believed to be C70 clusters. Vibrational Raman and infrared spectra have also been obtained for separated C60 and C70.
High temperature study of solid C-60, pristine and polymerized, was performed by Raman spectroscopy up to 843 K and 573 K respectively. The peak position of the A(g)(2) mode showed a strong and non-linear temperature dependence which can be interpreted as a result of anharmonic effects. The temperature dependence of the A(g)(2) mode, characteristic for C-60 dimers, linear C-60 chains and tetratalonal C-60, was tracked up to the depolymerization temperature and showed a behavior similar to pristine C-60 but with less softening. These data could be used also as a reference for in situ studies of C-60 chemical transformations which occur at high temperatures, e.g. polymerization and doping with alkali metals. (c) 2006 Elsevier Ltd. All rights reserved.
Surface-enhanced Raman scattering (SERS) was used to investigate C60 self-assembling in solvents like pyrrolidine (Py) and N-methyl-2-pyrrolidinone (NMP) as well as in binary mixtures of o-dichlorobenzene (DCB)/acetonitrile (ACN) and DCB/NMP. For a correct evaluation of the modifications of Raman spectra induced by the C60 aggregation, we have also presented the variations due to the measuring method, i.e., the signal dependence of the metallic support type and the surface roughness. The interaction between C60 and the Au substrate, appearing as a chemical component in SERS generation, is mainly evidenced by a band at ∼342 cm−1. In the aggregated phase, the intermolecular interactions lead to a reduction in the parent Ih C60 symmetry as observed by a modified phonon spectrum. As a general feature, the spectral range below 800 cm−1 is the most diagnostic for the aggregate assignment, the main indicative being the disappearance of the Raman bands associated to the radial vibration modes. SERS measurements have revealed two stages in the self-assembling of C60 in NMP. In the beginning, charge-transfer molecular complexes that associate slowly in stable aggregates are formed by the binding of an NMP molecule to the C60 cage. These complexes are noticed in the SERS spectrum by the replacement of the original Hg(1) band at ∼269 cm−1 with two others at ∼255 and ∼246 cm−1. In the aggregated phase, when using NMP and P as a solvent, the Raman spectrum reveals new bands that appear around 94 and 110–118 cm−1, which are associated with the interball interactions. In a DCB/ACN solvent mixture, the self-assembling process is driven by weak van der Waals type forces and resembles a precipitation, yielding C60 clusters of different size.
Icosahedral symmetry analysis is used to determine the eigenvalues and eigenvectors of a classical spring mass model of Buckyball. Several choices for spring constants are discussed and a comparison with spring mass systems of reduced symmetry is made. Dipole active normal modes are displayed stereographically.
Quantum-chemical results are reported which indicate that the absorption, fluorescence and phosphorescence spectra of Buckminsterfullerene are governed by a 1T1u ← 1Ag, 1T2g → 1Ag and 3T2g → 1Ag transition, respectively. Normal modes are calculated and their Franck-Condon and Jahn-Teller activity in these spectra are evaluated, along with the Jahn-Teller distortion of the radical anion. Vibrational progressions are expected to be short. A high phosphorescence quantum yield is predicted.
A transfer of fullerene C(60) to water was achieved by sonication of a two-phase system of water and C(60) in organic solvents, namely, benzene and toluene. Resulting aqueous dispersions were analyzed electrochemically, spectroscopically, by MALDI-MS and AFM methods. Samples prepared from benzene yield the formal redox potential very close to a value expected from the correlation of redox potentials and solvent donor numbers. However, these samples are not stable and C(60) precipitates out of the aqueous dispersion. Sonication of the toluene/water system produces stable system, in which the measured formal redox potential of C(60) is less negative. Stabilization of C(60) clusters in water is achieved by the presence of an organic amphiphile and spectroscopic methods indicate the presence of benzoate formed during sonication of a toluene/water mixture.
Surface enhanced Raman scattering (SERS) spectra of C60 (C70) were obtained in nonaqueous colloidal systems with newly developed methods. The enhancement factor was estimated to be over 10(5). This paper aims at the investigation of a fine influence mechanism for SERS in the nonliquid phase, which may help bring forth the perfect SERS mechanism. The detailed investigation is based on abundant comparative experiments where we found that the SERS effect is sensitive not only to the character of colloidal particles, dielectric constants, and polarizability, but also to the substrates, the solvent intermediate, and even the coating techniques. These detailed comparisons enrich the proofs of the SERS mechanism and provide a new way to optimize SERS systems.