Selected Area Electron Diffraction Data Research Articles

Automatic center identification of electron diffraction with multi-scale transformer networks

Selected area electron diffraction (SAED) is a widely used technique for characterizing the structure and measuring lattice parameters of materials. An autonomous analytic method has become an urgent demand for the large-scale SAED data produced from in-situ experiments. In this work, we realize the automatic processing for center identification with a proposed deep segmentation model named the multi-scale Transformer (MS-Trans) network. This algorithm enables robust segmentation of the central spots by combining a novel gated axial-attention module and multi-scale feature fusion. The proposed MS-Trans model shows high precision and robustness, enabling autonomous processing of SAED patterns without any prior knowledge. The application on in-situ SAED data of the oxidation process of FeNi alloy demonstrates its capability of implementing autonomous quantitative processing.© 2017 Elsevier Inc. All rights reserved.

Microstructure and gyromagnetic properties of low-sintered LiZnTi ferrite doped with nano-LiZn and V2O5 additives

In this study, nanoparticles of LiZn ferrite (nano-LiZn, 0.0–10.0 wt. %) fabricated via the sol-gel method and V2O5 particles were added into a Li0.43Zn0.27Ti0.13Fe2.17O4 (LiZnTi) ferrite to realize low temperature sintering. The effects of the nano-LiZn ferrite addition on the crystalline phase formation, microstructure, and magnetic properties of LiZnTi ferrite were systematically investigated. X-ray diffraction results reveal that the LiZnTi ferrite doped with nano-LiZn and V2O5 additives present a pure spinel structure, which can be explained by liquid phase of V2O5 and spinel structure of nano-LiZn, as revealed by high-resolution transmission electron microscopy and selected area electron diffraction data. Scanning electron microscopy images show that the addition of nano-LiZn leads to a change in the microstructure, with the grains becoming uniform and dense. Additionally, the variation in the saturation magnetization (Ms) depends on the LiZn content. In particular, Ms increases with increasing LiZn content from 2.0 to 10.0 wt. %. Finally, the LiZnTi ferrite doped 4.0 wt. % nano-LiZn and 0.60 wt. % V2O5 possesses a narrow ferromagnetic resonance linewidth of 197 Oe, a reduced coercivity of 192.6 A/m, and an improved bulk density of 4.73 g/cm3.

Automatic indexing of two-dimensional patterns in reciprocal space

An indispensable part of the structure determination of crystalline two-dimensional (2D) materials and epitaxial thin films is the correct indexing of the acquired diffraction patterns. In our previous work, we described an effective algorithm to determine the 3D unit-cell parameters of complex systems comprising different orientations and polymorphs. In this work, we adapt the indexing method to 2D lattices in reciprocal space. Analyzing low-energy electron diffraction and Fourier-transformed scanning tunneling microscopy measurements, the method is exemplarily applied to thin films of conjugated molecules like 3,4:9,10-perylenetetracarboxylic dianhydride (PTCDA), 6,13-pentacenequinone (P2O), and vanadyl phthalocyanine (VOPc) grown by physical vapor deposition on Ag(111). In all cases unit cells (rhomboids) along with their sixfold rotationally or mirror symmetric counterparts are determined. The already known commensurate epitaxial relationship is reproduced for PTCDA on Ag(111), demonstrating the validity of our method. In the case of P2O/Ag(111) a point-on-line epitaxial condition is found. Our algorithm can be equally well applied to all kinds of 2D patterns in reciprocal space where a crystallographic indexing is required, e.g., electron diffraction data [such as transmission electron diffraction, selected area electron diffraction (SAED)] and fast Fourier transforms (FFTs) of scanning probe images. To demonstrate this aspect, we evaluate FFTs of scanning tunneling microscopy data for stacked VOPc/PTCDA heteroepitaxial layers on Ag(111) as well as SAED data of an epitaxial ${\mathrm{TiO}}_{2}/{\mathrm{LaAlO}}_{3}(100)$ heterostructure in cross section.

Phytochemical Mediated Sol–Gel Synthesis, Crystallographic Structure, Morphology and Optical Investigations on ZnO Nanoparticles

Zinc oxide nanoparticles were synthesized through sol–gel technique using Azadirachta indica leaves extract. The formation of structure, crystallite parameters, size and morphology were studied through Fourier Transform Infrared spectroscopy, X-ray diffraction, Raman spectroscopy, Transmission Electron Microscopy (TEM) and Selected Area Electron Diffraction data records. X-ray diffraction peaks revealed the presence of hexagonal wurtzite structure for ZnO nanoparticles. The crystallite size and lattice strain of the prepared sample were respectively obtained through measuring the X-ray diffraction peaks broadening and Hall Williamson analysis using anisotropic and isotropic models. The estimated crystallite size using TEM, Scherrer formula and Hall Williamson models were found in well agreement with each other. The optical properties were investigated from the UV–Vis reflectance data and the photoluminescence spectrum recorded at room temperature. The chromaticity color coordinates obtained from the photoluminescence spectrum shows that the biosynthesized ZnO nanoparticles can be useful for white luminescence applications.

Crystal structure of incommensurate ηʺ-Cu1.235Sn intermetallic

Abstract The crystallographic parameters of the incommensurately ordered phase ηʺ of the composition Cu1.235Sn are reported. This phase belongs to the group of ordered Ni2In/NiAs-type phases, with a NiAs-type arrangement Cu(1)Sn and additional Cu(2) atoms partially occupying trigonal-bipyramidal interstices in an ordered fashion, leading to the formula Cu(1)Cu(2)0.235Sn = Cu1.235Sn. The structure model, afterward refined on the basis of powder X-ray diffraction data, has been derived on the basis of the slightly Cu-poorer commensurately ordered η′-Cu6Sn5 (=Cu1.2Sn) phase but also on previously reported commensurate structure models η8-Cu1.25Sn and η4+1-Cu1.243Sn derived from selected area electron diffraction data. In line with a recent work (Leineweber, Wieser & Hügel, Scr. Mater. 2020, 183, 66–70), the incommensurate ηʺ phase is regarded as a metastable phase formed upon partitionless ordering of the η high-temperature phase with absent long-range ordering of the Cu(2) atoms. The previously described η8 and η4+1 superstructure are actually of the same phase, and the corresponding superstructure models can be regarded as approximant structures of the ηʺ phase. The refined structure model is described in 3+1 dimensional superspace group symmetry C2/c(q 10-q 3)00 with a unit cell of the average structure with lattice parameters of a av = 4.21866(3) Å, b av = 7.31425(5) Å, c av = 5.11137(3) Å and b av = 90.2205(5)° and a unit cell volume V = 157.717(2) Å3. The modulation vector is with q 1 = 0.76390(4), q 3 = 1.51135(5), and governs the spatial modulation of the occupancy of the Cu(2) atoms described by a Crenel function. The occupational ordering is accompanied by displacive modulations of the atoms constituting the crystal structure, ensuring reasonable interatomic distances on a local level. In particular, the spatial requirements of pairs of edge-sharing Cu(2)Sn5 trigonal bipyramids (Cu(2)2Sn8) lead to a measurable splitting of some fundamental reflections in the powder diffraction data. This splitting is considerable smaller in η′-Cu1.20Sn, which lacks such pairs due to the lower Cu content.

Growth mechanism and domain structure study on epitaxial BiFeO3 film grown on (La0.3Sr0.7)(Al0.65Ta0.35)O3

A BiFeO3 (BFO) film is epitaxially grown on an (La0.3Sr0.7)(Al0.65Ta0.35)O3 (LSAT) substrate to investigate the lattice mismatch effect on the domain structure and lattice strain status within the BFO film. Atomic resolution scanning transmission electron microscope image, selected area electron diffraction (SAED) patterns, and X-ray reciprocal space mapping (XRSM) data clearly reveal that the lattice strain originating from the lattice mismatch between BFO and LSAT is relaxed by causing misfit dislocations in the BFO film. The SAED and XRSM data indicate that the crystal structure of BFO film is rhombohedral with the space group R3c. In particular, XRSM data acquired along two different in-plane orientations reveal that the BFO layer consists of two different domains that were 90° off each other with respect to the surface normal orientation. An atomistic model based on the crystal orientation relation found by SAED and XRSM shows that (1) the ferroelectric polarization axes of both domains are 35.6° with respect to the BFO film surface and (2) the two domains are consistent with the so-called 71° (and/or 109°) ferroelectric domains reported previously. The lattice mismatch of ∼2.8% calculated based on the epitaxial relation is proposed to be too large to be stored as elastic strain energy within the BFO layer.

Mechanochemical synthesis of a Ni3-xTe2 nanocrystalline composite and its application for simultaneous electrochemical detection of dopamine and adrenaline

A novel electrochemical sensor CPE/Ni3-xTe2 (carbon paste electrode modified with nickel telluride) was constructed for the simultaneous detection of the neurotransmitters dopamine (DA) and adrenaline (AD) in phosphate buffer solution (pH 7.0). The composite containing Ni3-xTe2 and Ni nanocrystals was synthetized by mechanochemical synthesis using ball milling procedures in an inert atmosphere, starting from Ni75Te25 powder mixtures. The samples were processed from 3 h to 20 h and characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy and magnetization. Rietveld analysis showed that Ni3-xTe2 and Ni nanocrystals have an average crystallite size of 10 nm and 4 nm, respectively, which was endorsed by transmission electron microscopy images and selected area electron diffraction data. The composite has ferromagnetic and superparamagnetic behavior governed by different sizes of the nanocrystalline Ni counterpart. The CPE/Ni3-xTe2 electrode showed electrocatalytic properties towards DA and AD with two separated peaks. The linear response range for the determination of both DA and AD was 4–31 μmol L−1 and the detection limits (S/N = 3) were 0.15 μmol L−1 and 0.35 μmol L−1 for DA and AD, respectively. Repeatability and stability studies are also provided to evaluate the applicability of a modified electrode. Hence, the CPE/Ni3-xTe2 represents a promising electrochemical platform for DA and AD quantification in various kinds of matrices, with preparation and operation routes totally based on green chemistry principles.

Depth dependent ferroelectric to incommensurate/commensurate antiferroelectric phase transition in epitaxial lanthanum modified lead zirconate titanate thin films

Transmission electron microscopy was used to investigate the coexistence of ferroelectricity (FE) and antiferroelectricity (AFE) in (001) and (011) (Pb0.97, La0.02) (Zr0.95, Ti0.05) O3 (PLZT) epitaxial thin films. The depth resolved selected area electron diffraction (SAED) results revealed that the AFE phase was located in the near interface region, whereas the FE phase was found in the near surface region. A thickness dependent lattice parameter distribution was calculated using the SAED data, and a decrease in the c/a ratio was found to correlate with the transition from AFE to FE stability. Additionally, commensurate and incommensurate modulations in AFE PLZT were identified based on the observation of various superlattice reflections.

Photochemical Synthesis and Catalytic Applications of Gold Nanoplates Fabricated Using Quercetin Diphosphate Macromolecules.

The demand for safer design and synthesis of gold nanoparticles (AuNPs) is on the increase with the ultimate goal of producing clean nanomaterials for biological applications. We hereby present a rapid, greener, and photochemical synthesis of gold nanoplates with sizes ranging from 10 to 200 nm using water-soluble quercetin diphosphate (QDP) macromolecules. The synthesis was achieved in water without the use of surfactants, reducing agents, or polymers. The edge length of the triangular nanoplates ranged from 50 to 1200 nm. Furthermore, the reduction of methylene blue was used to investigate the catalytic activity of AuNPs. The catalytic activity of triangular AuNPs was three times higher than that of the spherical AuNPs based on kinetic rate constants (k). The rate constants were 3.44 × 10–2 and 1.11 × 10–2 s–1 for triangular and spherical AuNPs, respectively. The X-ray diffraction data of gold nanoplates synthesized by this method exhibited that the nanocrystals were mainly dominated by (111) facets which are in agreement to the nanoplates synthesized by using thermal and chemical approaches. The calculated relative diffraction peak intensity of (200), (220), and (311) in comparison with (111) was found to be 0.35, 0.17, and 0.15, respectively, which were lower than the corresponding standard values (JCPDS 04-0784). For example, (200)/(111) = 0.35 compared to 0.52 obtained from the standard (JCPDS 04-0784), indicating that the gold nanoplates are dominated by (111) facets. The calculated lattice from selected area electron diffraction data of the as-synthesized and after 1 year nanoplates was 4.060 and 4.088 Å, respectively. Our calculations were found to be in agreement with 4.078 Å for face-centered cubic gold (JCPDS 04-0784) and literature values of 4.07 Å. The computed QDP–Au complex demonstrated that the reduction process took place in the B ring of QDP. This approach contributes immensely to promoting the ideals of sustainable nanotechnology by eradicating the use of hazardous and toxic organic solvents.

Effect of zinc doping on structural, magnetic and dielectric properties of perovskite (Tb0.874Mn0.106)MnO3−δ

The solid solutions (Tb0.874Mn0.106)Mn1−xZnxO3−δ (0.0 ≤ x ≤ 0.20) have been synthesized by the conventional solid state reaction. The effect of Zn doping on structural, magnetic, and dielectric properties of (Tb0.874Mn0.106)Mn1−xZnxO3−δ (0.0 ≤ x ≤ 0.20) has been discussed. All samples in the series crystallize in Pnma space group at room temperature confirmed by powder X-ray, neutron, and selected area electron diffraction data. Two magnetic orderings are found at 42 and 32 K for the x = 0.0 to 30 and 16 K for x = 0.20, respectively. The magnetic hysteresis loops showed that a transition occurs from metamagnetic to normal canted antiferromagnetic at lower temperatures. Dielectric constant anomaly was not found below 300 K.

Fabrication of miniaturized high bandwidth dielectric resonator on patch (DRoP) antenna using high dielectric CaCu3Ti4O12 nanoparticles

This paper deals with the performance evaluation of dielectric resonator on patch (DRoP) antenna using high dielectric CaCu3Ti4O12 nanoparticles (CCTO Nps) synthesized by low-temperature solution combustion method. X-ray diffraction pattern reveals that the optimum calcination temperature required for the formation of single phase CCTO Nps is 900 °C. Near-spherical morphology of CCTO Nps with nano size (∼100 nm) has been visualized using field emission scanning electron microscopic images. High-resolution transmission electron microscopic and selected area electron diffraction data reveal the cubic crystal system of CCTO Nps with preferential orientation of (220) plane. The low-frequency dielectric behaviors of CCTO Nps exhibit excellent properties like high dielectric constant (εr = 447) and low dielectric loss (tanδ = 0.42) at 30 °C. DRoP antenna fabricated using high dielectric CCTO Nps exhibits promising results such as wide bandwidth (540 MHz), good return loss (−21.23 dB) at 2.45 GHz and smaller in sizes (10.17 mm2), which is required for modern-day wireless communication systems.

Branch-like NiO/ZnO heterostructures for VOC sensing

We report for the first time on the synthesis of NiO/ZnO one-dimensional (1D) nanowire (NW) based heterostructures by applying a suitable methodology of transport and condensation. The synthesis involves, firstly the growth of NiO NWs on gold (Au) catalyzed alumina substrates using the vapor-liquid-solid (VLS) mechanism and then the formation of ZnO NWs directly on the NiO NWs using the vapor-solid (VS) mechanism. Sequential evaporation–condensation over Au-seeded alumina promotes the formation of NiO NWs, driven by the VLS growth mechanism. These NiO NWs act as backbones for the condensation of epitaxial ZnO nanostructures. The detailed morphological study of these heterostructures reveals that ZnO nanowires completely cover the whole NiO nanowires completely and growing out in the form of flat leaves from the NiO nanowire branches. The diameters of the NiO NWs have been found to vary from 15 nm to 60 nm. Selected area electron diffraction data (SAED) indicate an epitaxial growth of ZnO nanowires along (101)-planes on the strongly oriented NiO nanowires along (200) crystallographic planes. Finally, NiO NW and NiO/ZnO heterostructure based conductometric gas sensing devices have been fabricated and the comparison between their sensing performances have been compared. Interestingly, NiO/ZnO NWs heterostructure based sensing devices shows superior performance compared to NiO sensors toward volatile organic compounds (VOC).

Atomic channel occupation in disordered η-Al5Fe2 and in two of its low-temperatures phases, η″ and η‴

High-temperature, disordered η-Al5Fe2 intermetallic and its low-temperature long-range ordered structures have been investigated in the whole homogeneity range from 70.6 to 73.0 at.% Al based on selected area electron diffraction data and powder X-ray diffraction data. Using these data, the channel site occupation in the disordered η phase has been revised and a composition-dependent model with mixed occupation of the channels by both Al and Fe atoms was derived. It leads to an average number of atoms per channel and unit cell of approx. 1.5 in the whole homogeneity range. Below about 350 °C, four different phases exhibiting long-range order of the channel atoms appear to exist. Here the atomic ordering in the Al-poorest and Al-richest of these low-temperature phases, η″ and η‴ is reported. Both these phases can be characterized as incommensurately modulated composite crystal structures. Thereby, in both phases, the first composite subsystem contains atoms of the framework structure generating channels which are filled by atoms described by the second composite subsystem. The subsystems of the η″ phase have orthorhombic superspace groups Xmcm(00g)0s0 and Immm(00g)0s0 keeping the basic metric of the parent η phase. The subsystems of the η‴ can be described by the monoclinic superspace groups P21/c(0b0)00 and P21/c(0b0)s0 providing a lattice correspondence am = 1/2(a+b), bm = c and cm = a+b to the orthorhombic parent η phase. Although the number of atoms per channel is approx. 1.5 in η″ and η‴ phases, the channels are differently correlated with each other which is attributed to different Fe content in the channels inherited from the channel occupation in the disordered η phase.

Nanostructural investigation of slightly altered rhyolitic volcanic glass

Silica rich volcanic glass is investigated by selected area electron diffraction (SAED) and high resolution electron microscopy (HRTEM), and nanostructural characterization is presented. In freshly crushed glass shards the presence of amorphous and randomly oriented nanocrystalline component was detected, the latter one enriched in iron with respect to the amorphous regions. To interpret the iron containing nanocrystalline structure, model clusters of different size, shape and composition were constructed and used to calculate scattered electron intensity. According to our calculations, already a single ring of six interconnected SiO4 tetrahedra results a separate broad peak at ~5Å which reflects nicely the main diffraction feature of amorphous silica. Inserting two dimensional iron array between two neighbouring silica layers produces a less compact structure and the first diffraction peak shifts towards larger values with respect to the pure silica. For smaller clusters (number of atoms<250) first peak position shows a remarkable dependence on the structure and size of the cluster. The pair distribution analysis of SAED and HRTEM data indicates a certain degree of ordering with a domain size of ~2nm.

Superconductivity of Perovskite Ba1−x Y x (Bi0.2Pb0.8)O3−δ

Solid solution Ba1−x Y x (Bi0.2Pb0.8)O3−δ with 0.00 ≤ x ≤ 0.085 has been prepared by tradition high-temperature reaction under 840 °C. X-ray and selected area electron diffraction data confirm that the samples in this solid solution crystallize in space group P1 at room temperature. X-ray photoelectron spectroscopy data indicate that the valence of bismuth in this solid solution is + 5 while the valence of lead is both + 2 and + 4. Temperature-dependent magnetic susceptibility and resistivity of the studied samples show that superconductivity can be observed for Ba1−x Y x (Bi0.2Pb0.8)O3−δ with 0.00 ≤ x ≤ 0.04. The transition temperature (\(T_{\mathrm {c}}^{\text {zero}}\)) decreases with the increase of Y in the sample, which is attributed to the increase of electronegativity of the cations.

Revealing the nanostructure of calcium phosphate coatings using HRTEM/FIB techniques

Herein, we report on the micro- and nanostructure of the calcium phosphate coating produced by pulsed laser deposition (PLD), using focused ion beam (FIB) lamella sample preparation and transmission electron microscopy (TEM) as the characterization technique. The initial selected area electron diffraction (SAED) data demonstrated the presence of hydroxyapatite (HA) over any other possible calcium phosphate crystalline structure and the polycrystalline nature of the coating. Moreover, the SAED analyses showed clear textured ring patterns coherent with the presence of a preferred orientation in the HA nano-crystal growth. The SAED data also indicated that the coating appears to be textured in the 〈002〉 crystalline direction. Dark-field images obtained using 002 as the working reflection showed a clear oriented crystal growth in columns, from bottom to top. These columns have a peculiar arrangement of nano-crystals since, in some cases, the preferred orientation appears to start at a certain distance from the substrate. Direct d-spacing measurements on high-resolution TEM images provided further proof of the presence of an HA nano-crystal structure. The reported data may be of interest in the future to adjust the microstructure of the HA coatings.

On the discrimination of semi-graphite and graphite by Raman spectroscopy

Graphite samples from several mines (Austria, Brazil, China, Madagascar, Mozambique, Norway, Russia, Sri Lanka and Ukraine) were investigated by reflectance measurements, X-ray-diffraction, high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and Raman spectroscopy. X-ray-diffraction indicates that the structural order of the carbonaceous matter (CM) varies in dependence on the metamorphic rank of the host rock. Semi-graphite is found in lower greenschist facies samples from the Kaisersberg mine (Austria). At the nanoscale, micropores characterize semi-graphite. They are polygonized in the transition zone between semi-graphite and graphite. During progressive graphitization within the greenschist facies, semi-graphite is transformed continuously to graphite. HRTEM images and SAED data show a transformation of the microporous nano-texture to a predominantly lamellar texture. Perfect graphite is observed in samples from the granulite facies. Raman spectroscopy mirrors this evolution. The observed spectral characteristics, the width of the Raman G band and the D1/(G+D1+D2) area ratio of the CM Raman spectrum discriminate semi-graphite and graphite.

Stacking disorder in silicon carbide supported cobalt crystallites: an X-ray diffraction, electron diffraction and high resolution electron microscopy study.

Supported cobalt Fischer-Tropsch catalysts are characteristically nanoparticulate and the reduced SiC supported catalyst was found to contain both HCP and FCC polymorphs. This is reflected in the powder XRD patterns and generally there is a poor fit between the experimental and calculated diffractograms. This was ascribed to small crystallite sizes and the occurrence of disorder, manifested as peak broadening and peak shifts. Selected area electron diffraction data of suitably oriented cobalt catalyst grains on silicon carbide supports show non-periodic disorder in the zone axis orientations that contain the common (001) (HCP) and (111) (FCC) reciprocal lattice planes. Both FCC and HCP polymorphs are present in the same grains and these show disorder mainly in the HCP component. The disorder is further examined using high angle annular dark field (HAADF) scanning transmission electron microscopy at atomic resolution and the stacking sequences elucidated. Random sequences of mainly FCC are interrupted by HCP sequences and twin surfaces with reverse stacking sequences are also present. This study highlights the presence of significant disorder in cobalt catalyst grains confirmed by HAADF microscopy.

Copper-based nanoparticles prepared from copper (II) acetate bipyridine complex

We report the synthesis of CuO, Cu/Cu2O and Cu2O/CuO nanoparticles (NPs) from the single copper (II) acetate bipyridine complex by three different methods:microwave-assisted, solvothermal and borohydride. Presence of bipyridine ligand in the copper complex would impose no need in additional stabilization during synthesis. The phases of formed NPs were identified by X-ray diffraction. CuO NPs of ~11 nm were obtained via solvothermal synthesis from alkaline solution at 160?C. The Cu/Cu2O NPs of ~80 nm were produced via microwave-assisted polyol procedure at 185-200?C, where ethylene glycol can play a triple role as a solvent, a reducing agent and a surfactant. The Cu2O/CuO NPs of ~16 nm were synthesized by a borohydride method at room temperature. Interplanar spacing calculated from the selected-area electron diffraction data confirmed the formation of Cu, CuO and Cu2O phases in respective samples. All NPs are stable and can be used for various applications including biomedicine.

Studies on linear, nonlinear optical and excited state dynamics of silicon nanoparticles prepared by picosecond laser ablation

We report results from our studies on the fabrication and characterization of silicon (Si) nanoparticles (NPs) and nanostructures (NSs) achieved through the ablation of Si target in four different liquids using ∼2 picosecond (ps) pulses. The consequence of using different liquid media on the ablation of Si target was investigated by studying the surface morphology along with material composition of Si based NPs. The recorded mean sizes of these NPs were ∼9.5 nm, ∼37 nm, ∼45 nm and ∼42 nm obtained in acetone, water, dichloromethane (DCM) and chloroform, respectively. The generated NPs were characterized by selected area electron diffraction (SAED), high resolution transmission microscopy (HRTEM), Raman spectroscopic techniques and Photoluminescence (PL) studies. SAED, HRTEM and Raman spectroscopy data confirmed that the material composition was Si NPs in acetone, Si/SiO2 NPs in water, Si-C NPs in DCM and Si-C NPs in chloroform and all of them were confirmed to be polycrystalline in nature. Surface morphological information of the fabricated Si substrates was obtained using the field emission scanning electron microscopic (FESEM) technique. FESEM data revealed the formation of laser induced periodic surface structures (LIPSS) for the case of ablation in acetone and water while random NSs were observed for the case of ablation in DCM and chloroform. Femtosecond (fs) nonlinear optical properties and excited state dynamics of these colloidal Si NPs were investigated using the Z-scan and pump-probe techniques with ∼150 fs (100 MHz) and ∼70 fs (1 kHz) laser pulses, respectively. The fs pump-probe data obtained at 600 nm consisted of single and double exponential decays which were tentatively assigned to electron-electron collisional relaxation (&amp;lt;1 ps) and non-radiative transitions (&amp;gt;1 ps). Large third order optical nonlinearities (∼10−14 e.s.u.) for these colloids have been estimated from Z-scan data at an excitation wavelength of 680 nm suggesting that the colloidal Si NPs find potential applications in photonic devices.