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This article presents an 8-bit time-domain analog-to-digital converter (ADC) achieving ten-GS/s conversion speed with only two time-interleaved (TI) channels. A successive approximation register (SAR) time-to-digital converter (TDC) is implemented for the subpicosecond resolution time quantization with high power/area efficiency and low jitter. The throughput of the SAR TDC is enhanced by a unique delay-tracking pipelining technique to enable a 5-GS/s single-channel conversion. On the circuit level, the reference time generation for the SAR TDC is realized by the proposed selective delay tuning (SDT) cell for high efficiency and small reference time variation. Fabricated in the 14-nm FinFet CMOS technology, this ADC achieves a 37.2-dB signal-to-noise and distortion ratio (SNDR) and a 50.6-dB spurious-free dynamic range (SFDR) at the Nyquist input frequency, leading to a 24.8-fJ/conv-step Walden figure of merit with an active area of only 2850 $\mu \text{m}^{2}$. [ABSTRACT FROM AUTHOR]

Results of quantum density functional theory (B3LYP) calculations on the decomposition of NO to N2O in the presence of Cu are reported. Three approaches of NO interacting with Cu and two decomposition channels via cis- and trans-(NO)2 dimers have been identified. The configuration of NO approaching to the Cu atom with N is more stable than the other two configurations, in which the NO interacts with Cu via oxygen. At low temperature, NO is in favor of decomposing to N2O via the trans-intermediate Min6 in the presence of Cu atom, because the decomposition activation energy of this channel is only 61.1 kJ/mol at the B3LYP/Lanl2DZ level, and lower than the other decomposition channel''s. The potential energy surface shows that the cis-intermediate Min8 is highly stabilized both thermodynamically and kinetically at low temperature, and the calculation results also suggest that the N–O bond is more easily dissociated than the Cu–O bond in the Min8. Hence, it is very different for the NO decomposition between in the gas phase and in the presence of Cu. [Copyright &y& Elsevier]

Nanoscale CdS colloid has exhibited great second-order optical nonlinearities measured by hyper-Rayleigh scattering (HRS) technique. Here a further study on electrolyte concentration dependence of HRS signal of nanoscale CdS colloid is carried out in order to exclude the possible contributions of some third-order nonlinear optical processes based on colloidal particle surface electric field and solvent field. Results show that the HRS signal remains unchanged with increasing electrolyte concentration, implying that the HRS signal arises indeed from second-order polarization (including bulk-like polarization and surface polarization) of CdS nanoparticles rather than the third-order processes. Furthermore, HRS signal variation during the formation of CdS colloid is studied for the first time. An obvious enhancement of HRS signal intensity is observed immediately once Cd2+ and S2− ions are mixed. After that, HRS signal decreases toward a constant value with time. This is explained in terms of surface contribution due to large surface-to-volume atomic ratio for nanoparticles. [Copyright &y& Elsevier]

Hyper-Rayleigh scattering (HRS) or incoherent second harmonic generation (SHG) technique has been used to investigate the second-order optical nonlinearities of nanoparticles and seems sensitive to nanoparticle surfaces. Here, more direct evidence that shows the importance of surfaces for HRS response of nanoparticles was experimentally obtained. Two CdS nanoparticles of 3 nm average diameter with different surface-capping molecules, CdS/AOT-SO3− (AOT-SO3− is anion of bis (2-ethylhexyl) sulfosuccinate, disodium salt) and CdS/Py/AOT-SO3− (Py represents pyridine molecule), were studied by HRS technique. The “per particle” first-order hyperpolarizability β values were evaluated to be 3.98×10−27 esu for the CdS/AOT-SO3− and 2.63×10−27 esu for the CdS/Py/AOT-SO3− nanoparticles. A reduction in β value is found when AOT-SO3− on CdS nanoparticle surface is replaced by pyridine. Similarly, the reduction of HRS signal intensity of a solution containing the CdS/AOT-SO3− nanoparticles was observed when increasing pyridine concentration in the solution. Furthermore, the dynamic process of the surface-capping molecule exchange was studied by detecting both HRS signal intensity and electroconductivity variations with time. Possible effect mechanism is discussed in terms of a two-level model approximation derived from molecular chromophores, when considering the influence of different surface-capping molecules on the polarity of Cd&z.sbnd;S bonds at nanoparticle surfaces. [Copyright &y& Elsevier]