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Search for "decay time" in Full Text gives 27 result(s) in Beilstein Journal of Nanotechnology.
Dual-heterodyne Kelvin probe force microscopy
Beilstein J. Nanotechnol. 2023, 14, 1068–1084, doi:10.3762/bjnano.14.88
- (SPV decay time constant) images can be mapped by appropriately fitting the amplitude spectrum. As with AM-heterodyne KPFM, there is a frequency mixing effect due to the capacitance term, and we restrict ourselves to the first harmonic to describe the time response of the capacitance gradient (K1
- our previous pp-KPFM measurements on PTB7:PC71BM blends [4][11], which showed that the SPV decay time constant can vary from tens of µs to several hundreds of µs, depending on the morphology and phase composition. Doing so, we maximized our chances to generate a time-dependent SPV (which first
- harmonic could be mapped by DHe-KPFM) by choosing a pump time-period higher than a few ms (i.e., the order of magnitude of the longest decay time constants that we observed so far in this system [4]). Naturally, at this stage, the contrasts observed do not allow us to conclude as to the nature of the SPV
A visible-light photodetector based on heterojunctions between CuO nanoparticles and ZnO nanorods
Beilstein J. Nanotechnol. 2023, 14, 1018–1027, doi:10.3762/bjnano.14.84
- difficult to reach, which increases the required decay time [47]. To evaluate the photodetector performance, some essential parameters are considered. The responsivity (R) is used to determine the applicability of the visible-light photodetector. R, which is defined as the photocurrent divided by the
Plasmonic nanotechnology for photothermal applications – an evaluation
Beilstein J. Nanotechnol. 2023, 14, 380–419, doi:10.3762/bjnano.14.33
LED-light-activated photocatalytic performance of metal-free carbon-modified hexagonal boron nitride towards degradation of methylene blue and phenol
Beilstein J. Nanotechnol. 2022, 13, 1380–1392, doi:10.3762/bjnano.13.114
- , lower charge transfer resistance, and improved charge carrier density (2.97 × 1019 cm−3). This subsequently enhanced the photocurrent density (three times) and decreased the photovoltage decay time (two times) in comparison to those of HBN. The electronic band structure (obtained through Mott–Schottky
- a voltage buildup which subsequently decayed upon quenching of the light source [31]. The obtained photovoltage plots were subsequently fitted with an exponential decay curve. The MBN-80 demonstrated a reduced decay time (4.55 s) in comparison to that of HBN (2.65 s) emphasizing an efficient charge
Near-infrared photoactive Ag-Zn-Ga-S-Se quantum dots for high-performance quantum dot-sensitized solar cells
Beilstein J. Nanotechnol. 2022, 13, 1337–1344, doi:10.3762/bjnano.13.110
- efficient photoanode for QDSCs and it produces more electron–hole pairs, which helps to improve the photocurrent density. Time-resolved photoluminescence (TRPL) studies were carried out to evaluate the electrons decay time of AZGSSe/TiO2. The decay curve was fitted with a biexponential function [33] and it
Ultrafast signatures of magnetic inhomogeneity in Pd1−xFex (x ≤ 0.08) epitaxial thin films
Beilstein J. Nanotechnol. 2022, 13, 836–844, doi:10.3762/bjnano.13.74
- , Figure 1a, the first two terms in Equation 1 are sufficient. The fast component with an amplitude Af has a decay time = 0.24 ± 0.02 ps. The lifetime of the second, slow component with the amplitude As is = 410 ± 10 ps. Figure 1b–d shows similar dynamics of the reflectance for three films with iron
Electrochemical nanostructuring of (111) oriented GaAs crystals: from porous structures to nanowires
Beilstein J. Nanotechnol. 2020, 11, 966–975, doi:10.3762/bjnano.11.81
- was used. An optical filter was used to select radiation from the near-IR spectral range (700–2500 nm, optical power 130 mW). The current through the samples was measured by means of a Keithley’s Series 2400 source measure unit. Since the photoconductivity decay time is long enough, a mechanical
Hexagonal boron nitride: a review of the emerging material platform for single-photon sources and the spin–photon interface
Beilstein J. Nanotechnol. 2020, 11, 740–769, doi:10.3762/bjnano.11.61
- function for the fluorescence light of a 2-level system is at τ = 0, g(2)(τ) = 0. Therefore, a non-resonantly driven 2-level system behaves as an SPS, emitting light in the SP state. The anti-bunching decay time τ0 for zero excitation power (i.e., k12 = 0) is τ0(P → 0) = 1/k12. Since k12 is the decay time
- τ1, τ2 and the coefficient c are given by In the above g(2)(τ) function, τ1 represents the anti-bunching decay time and τ1 represents the bunching process (Figure 1d). This is because the rates k23 and k31 are much smaller compared to k21, τ1 ≪ τ2. This means that the antibunching process occurs at a
- optical modulation of the fluorescence by exciting with a 1064 nm laser that populated a dark state, followed by decay to the ground state. The excited-state lifetime of 5.6 ns and the second photon correlation decay time of 250 ns and 321 ns provide a NIR modulation of 10–20%. Due to the larger size of
Implementation of data-cube pump–probe KPFM on organic solar cells
Beilstein J. Nanotechnol. 2020, 11, 323–337, doi:10.3762/bjnano.11.24
- time-averaged SP. This may lead to a frequency-dependent overestimation of the average SP and consequently generate errors in the mathematical fit performed on the SP(fmod) curves, which is done to calculate the SPV decay-time constants. Last, the analysis of IM-KPFM data becomes a complex matter when
- pulses. However, it is important to note that the data acquired using these two different sequences display an excellent consistency. At the irradiance maximum (Popt = 193 mW∙cm−2, Figure 6a and Figure 6b), the decay-time constants, stretch exponents and dark-state SP values extracted from both curves
- (Figure 6). However, the decay-time constant is barely fluence-dependent, which indicates that the underlying dynamics originate from trap-delayed processes [25]. Most likely, a broad distribution of states exists in which the photocarriers are trapped for longer or shorter periods as indicated by stretch
Plasmonic nanosensor based on multiple independently tunable Fano resonances
Beilstein J. Nanotechnol. 2019, 10, 2527–2537, doi:10.3762/bjnano.10.243
- phase difference effect, and its equations are expressed as follows where an and ωn are the field amplitude and resonant frequency of the nth mode, respectively. τn0 is the decay time of internal loss of the nth mode in a resonant system. τn1 and τn2 are the decay time of the coupling between the
- g has a great influence on the transmittance and the FWHM. When g is increased, the decay time τn of the coupling between the resonant system and the waveguide will increase, and this can lead to the decrease in transmittance and FWHM, which is exactly in agreement with the theoretical analysis of
Review of time-resolved non-contact electrostatic force microscopy techniques with applications to ionic transport measurements
Beilstein J. Nanotechnol. 2019, 10, 617–633, doi:10.3762/bjnano.10.62
- between a Pt-coated AFM tip and a gold substrate (separated by about 20 nm) under high vacuum (ca. 10−6 mbar, Jeol JSPM-5200) to simulate ionic transport in the sample with a known decay time constant. Note that a separation ≥1 nm is necessary in general to ensure that no charge is injected into the
- rates presented as spatial mapping of τFP. These results can still provide useful insight into sample dynamics (in this case the quantum efficiency of the photovoltaic material) even though direct quantitative measurements of decay time constants may not always be possible. Phase-kick EFM Background and
- ± 3 ns. Note that a decay time of 190 ns is ca. 300-times faster than the cantilever oscillation period. Measured tip–sample force as a function of the distance for a gold-coated tip over a grounded gold substrate (red) and a grounded 200 μm thick sapphire substrate (blue) with 4 V applied to the tip
Numerical analysis of single-point spectroscopy curves used in photo-carrier dynamics measurements by Kelvin probe force microscopy under frequency-modulated excitation
Beilstein J. Nanotechnol. 2018, 9, 1834–1843, doi:10.3762/bjnano.9.175
- modulation frequency. The spectroscopy curve is then fitted using mathematical models that enable one to determine the time constant(s) associated to the measured SPV dynamics. One of the advantages of FMI-KPFM compared to similar techniques is that in FMI-KPFM, images of the SPV decay time constant can be
- the SPV in photoactive materials [3][4][5][6][8]. Under this premise, we can model the SPV behavior of a photovoltaic material under modulated excitation as a function of the time for both the built-up and decay in the following way for the case of a single SPV built-up and decay time constant
- (Equation 1 and Equation 2) and for a more general case with k build-up and l decay time constants (Equation 3 and Equation 4): Here, p is the time duration of the excitation pulse, i is the duration of time between the pulses, τb is the time constant associated to SPV built-up, and τd is the time constant
Multimodal noncontact atomic force microscopy and Kelvin probe force microscopy investigations of organolead tribromide perovskite single crystals
Beilstein J. Nanotechnol. 2018, 9, 1695–1704, doi:10.3762/bjnano.9.161
- on the basis of a single time constant decay. In addition, the time-resolved measurements have been carried out as a function of the fluence. As expected, the increase in charge carrier density (for increasing optical powers) leads to a decrease in the decay time (Figure 5c). More precisely, τd
- photovoltage (TPV) measurements reported for MAPb(I1−x,Brx)3 perovskite thin films [37]. Besides, the similarity with the decay time values obtained by TPV measurements on MAPbI3 single crystals [38] is remarkable (e.g., τd = 175 μs under 10 mW/cm2 illumination for FMI-KPFM measurements on MAPbBr3, and τd
- polarity. (b) Experimental curves of the average surface potential as a function of the illumination modulation frequency Fmod acquired at 515 nm with an optical peak power of 2.95 mWcm−2. The result of the numerical fit performed to extract the SPV decay time constant is displayed by a solid line. (c
Photoluminescence of CdSe/ZnS quantum dots in nematic liquid crystals in electric fields
Beilstein J. Nanotechnol. 2018, 9, 1544–1549, doi:10.3762/bjnano.9.145
- matrix without reorientation of the LC molecules. With increasing electric field strength, the quenching of QDs luminescence occurred in the active LC matrix, while the PL intensity did not change in the passive LC matrix. The change in the decay time with increasing electric field strength was similar
- obtained results are interesting for controlling the PL intensity of semiconductor QDs in liquid crystals by the application of electric fields. Keywords: aggregation; decay time; liquid crystal; luminescence intensity; orientation; Introduction Colloidal quantum dots (QDs) are a special kind of
- change their orientation. We have studied intensity and a decay time of QD photoluminescence as well as the change of particle size and distribution of QDs and ion current in the LC matrix. Experimental We used hydrophobic CdSe/ZnS quantum dots with a core diameter of 5 nm obtained from Belarusian State
Surface-plasmon-enhanced ultraviolet emission of Au-decorated ZnO structures for gas sensing and photocatalytic devices
Beilstein J. Nanotechnol. 2018, 9, 771–779, doi:10.3762/bjnano.9.70
- insightful information for depicting the fast charge carriers as well as to elucidate the mechanism of charge transfer, TRPL spectra were recorded at room temperature for all samples (Figure 3d). The fast decay time (fast and slow), as extracted by fitting the bi-exponential curve at the 385 nm emission peak
- , was equal to 150 ps and 995 ps for Au NP/ZnO samples, respectively. This is comparable to the values for ZnO found to be 197 ps and 1.05 ns, respectively. This may imply that the charge transfer occurring between the Au NPs and ZnO is responsible for the faster decay time components due to exciton
Changes of the absorption cross section of Si nanocrystals with temperature and distance
Beilstein J. Nanotechnol. 2017, 8, 2315–2323, doi:10.3762/bjnano.8.231
- (Iex) and even τA: However, the Auger decay time τA is not easily determined (literature reports values within a broad range from picoseconds [15] to nanoseconds [16]). Therefore, we have to avoid strong-pumping regimes where double-excitation of NCs takes place. Assuming N2/N1→0 we have IexστA→0 (see
- we demonstrated that special attention needs to be paid to the excitation pulse length [24]. Here we show how to utilize the knowledge of the average ON lifetime. According to Equation 8 the PL onset kinetics for the two fitting models are described as: The average PL decay time of photons can be
Sub-nanosecond light-pulse generation with waveguide-coupled carbon nanotube transducers
Beilstein J. Nanotechnol. 2017, 8, 38–44, doi:10.3762/bjnano.8.5
- extracted from a time-domain histogram (Figure 4e, measured with SNSPD) is somewhat larger than the theoretically expected value, which could be due to the decay time of electrical pulses τpulse ≈ 80 ps, as measured on chip (Figure 4e, black line). Moreover, the cumulative timing jitter of detector, pulse
- generator and connectors lead to additional broadening of the light pulse and thus increase of the measured decay time. Due to these instrumental restrictions, we are not able to determine the upper limit of the switching rate for the presented waveguide-coupled CNT-based light emitter. However, even the
- frequencies of 0.2, 0.5, 1 and 2 GHz. (e) The decay of the CNT-emission following the trailing edge of an electrical pulse (black line) was measured with the slow SPAD (blue symbols) and fast SNSPD (red symbols) along with fitted exponential decay curve (decay time τ = 79 ps). The broadening of the electrical
Effect of Anderson localization on light emission from gold nanoparticle aggregates
Beilstein J. Nanotechnol. 2016, 7, 2013–2022, doi:10.3762/bjnano.7.192
- correlates to the amount of material corresponding to the given decay time. The values show that the emission is faster in the case of quartz than on glass and in colloidal form. This can be due to the occurrence of a different distribution of hot spots where the optical field is highly localized due to the
Electronic interaction in composites of a conjugated polymer and carbon nanotubes: first-principles calculation and photophysical approaches
Beilstein J. Nanotechnol. 2015, 6, 1138–1144, doi:10.3762/bjnano.6.115
- prevent any exciton recombination (in absence of annihilation), therefore raising the probability of exciton separation and promotion of PC. The total decaying population is where the Ai are proportional to the PL intensity from levels i. We define an average decay time of the photogenerated charge
Effects of surface functionalization on the adsorption of human serum albumin onto nanoparticles – a fluorescence correlation spectroscopy study
Beilstein J. Nanotechnol. 2014, 5, 2036–2047, doi:10.3762/bjnano.5.212
- function. Its amplitude at time 0 scales with the inverse NP concentration; the characteristic decay time, τD, scales with the hydrodynamic radius, RH, of the diffusing NPs. Normalized fluorescence intensity autocorrelation curves of (a) DHLA- and (b) DPA-stabilized QDs dissolved in PBS without (blue) and
Photoresponse from single upright-standing ZnO nanorods explored by photoconductive AFM
Beilstein J. Nanotechnol. 2013, 4, 208–217, doi:10.3762/bjnano.4.21
- V. Such a high bias was applied to ensure a well detectable response. In order to determine the rise and decay time constants, we applied several cycles of illumination using white light (full spectrum) of the Xe lamp at 150 W. The optical properties of ZnO NRs have been characterized
- 12 mA, followed by an exponential current decrease (blue shaded area in Figure 4a), which can be fitted well by: where t is time, τ is the decay time constant, t0 is the decay time offset, I0 and C1 are the offset and amplitude of the current decay, respectively. The time constant of the dark current
- instabilities in the form of pronounced current spikes and slumps, which appear randomly and originate likely from mechanical instabilities in the tip-to-sample contact. At t = 1835 s the current abruptly decreases, which again can be well fitted by Equation 1. In this case the best fit yields a decay time
Diamond nanophotonics
Beilstein J. Nanotechnol. 2012, 3, 895–908, doi:10.3762/bjnano.3.100
- 1 summarizes the observed decay constants. For all resonators, the decay time is reduced by about a factor of four compared to an uncoupled color center. The strongest coupling is observed with the bow-tie resonator. 3 Dielectric diamond photonics While plasmonic resonators focus on strong coupling
Ultraviolet photodetection of flexible ZnO nanowire sheets in polydimethylsiloxane polymer
Beilstein J. Nanotechnol. 2012, 3, 353–359, doi:10.3762/bjnano.3.41
- enhanced photoconduction. PDMS coating results in a reduced response speed compared to that of a ZnO nanowire film in air. The rising speed is slightly reduced, while the decay time is prolonged by about a factor of four. We conclude that oxygen molecules diffusing in PDMS are responsible for the UV
- Figure 4d on a logarithmic scale. The maximum photocurrent of the device in air is 86 μA, while that of the device in PDMS reaches 476 µA. The PDMS coating over ZnO nanowires leads to an enhancement of the UV photosensitivity and prolongs the decay time. The rise of the photocurrent and the dark current
- of the maximum seen upon UV illumination. We define the dark current decay time as the time taken for the current to decay to 10% of the peak value. For the nanowire film in air the decay time is about 7 s, as shown in Figure 4f, whereas for that in PDMS the decay time is 29 s, i.e., about four times
Pulse-response measurement of frequency-resolved water dynamics on a hydrophilic surface using a Q-damped atomic force microscopy cantilever
Beilstein J. Nanotechnol. 2012, 3, 260–266, doi:10.3762/bjnano.3.29
- previous report on step-response measurement, the response signal in the cantilever deflection exhibited a substantially longer decay time in the proximity of a mica substrate in water [25]. In the present experiment the result seems quite the contrary, that is, the decay time seems to be rather shortened
- relax until it reaches a new equilibrium state. This effect leads to a lateral flow of the fluid and is detected as a long decay time of the cantilever position and hence a large apparent drag coefficient [31]. This lateral flow is considered to cause coupling between the longitudinal response of the
Highly efficient ZnO/Au Schottky barrier dye-sensitized solar cells: Role of gold nanoparticles on the charge-transfer process
Beilstein J. Nanotechnol. 2011, 2, 681–690, doi:10.3762/bjnano.2.73
- (nonradiative path), observed here, indicates an efficient electron transfer from the sensitizer to the semiconductor system. The various decay time constants obtained after deconvolution of the fluorescence decay curves (Figure 5b) with the instrument response function (IRF) are given in Table 3. The fraction
- . We have observed similar fluorescence-decay time constants (τ3) in both ZnO-nanorod and ZnO/Au-nanocomposite systems, indicating that the dynamics of the charge-transfer process from the surface-adsorbed sensitizer to the CB of the semiconductor is the same in both systems. In contrast, a very low
- electron population in the slow decay path (τ1 in Table 3) indicates that much less recombination of electrons occurs at the C343/semiconductor interface. The longer decay time constant observed in the case of the ZnO/Au-nanocomposite system (3.282 ns) compared to the bare ZnO-nanorod system (2.508 ns
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