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Atmospheric aerosol particles affect air pollution, public health, and radiative forcing of climate. Their phase state and morphology have far ranging effects on gas uptake, particle phase rate of reaction and aging. Recent reports have demonstrated that atmospheric particles may exist in semi–solid or glassy solid states. The phase transition between these two states occurs at the glass transition temperature (Tg). The goal of Chapters 2 and 4 of this work was to predict the phase state and viscosity of secondary organic aerosol (SOA) mixtures. A modeling approach to predict viscosity as a function of ambient temperature and relative humidity (RH) that uses a parameterization for estimating Tg of organic compounds from molecular composition is presented. The method is applied to α–pinene and isoprene SOA using marker compounds and toluene and diesel-derived SOA using high–resolution mass spectrometry (HRMS) data. Predictions agree well with measured viscosities. Finally, the viscosity of biomass burning SOA is predicted with two sets of HRMS data collected using different ionization techniques, electrospray ionization and atmospheric pressure photoionization, on the same samples. The use of different ionization techniques leads to a difference of ~102 in predicted viscosity at low RH.Next, measurements of the reactive uptake of dimethylamine (DMA) by ammonium sulfate (AS) and mixed AS–sucrose particles at different RH are simulated with the kinetic multi–layer model of gas particle interactions (KM-GAP) in Chapter 3. Investigations into the role of amines in new particle formation and nano–particle growth are essential to our understanding of cloud condensation nuclei. KM-GAP is well suited to elucidating the mechanisms underlying amine uptake as it explicitly treats the temporal evolution of all species from the gas phase to the particle. Particle mass growth over time and its humidity dependence is successfully reproduced for all experimental samples. Uptake in the mixed AS–sucrose particles is limited by diffusion of DMA and AS through a viscous sucrose–rich shell at lower RH. Uptake coefficients increase when RH increases, but decrease when the molar fraction of sucrose increases at fixed RH. The model is extrapolated to emulate atmospheric conditions. At RH greater than or equal to 70% for liquid particles, amine uptake can lead to a mass increase of approximately 20 to 60%.

Unexpectedly high amounts of aminium salts have been detected in ambient aerosol particles, prompting investigations into their role in new particle formation and nanoparticle growth. Amine uptake ...

1/ ${f}$ noise is characterized on thick and thin-gate oxide-based FinFETs for different channel lengths. The devices exhibit gate bias dependence in 1/ ${f}$ noise even in the weak-inversion region of operation which cannot be explained by the existing flicker noise model. We attribute this phenomenon to the non-uniform oxide-trap distribution in energy or space. Based on our characterization results for n- and p-channel FinFETs, we have improved the BSIM-CMG industry standard compact model for the FinFETs. The improved model is able to capture the 1/ ${f}$ noise behavior over a wide range of biases, channel lengths, fin numbers, and number of fingers.

Information on liquid–liquid phase separation (LLPS) and viscosity (or diffusion) within secondary organic aerosol (SOA) is needed to improve predictions of particle size, mass, reactivity, and cloud nucleating properties in the atmosphere. Here we report on LLPS and viscosities within SOA generated by the photooxidation of diesel fuel vapors. Diesel fuel contains a wide range of volatile organic compounds, and SOA generated by the photooxidation of diesel fuel vapors may be a good proxy for SOA from anthropogenic emissions. In our experiments, LLPS occurred over the relative humidity (RH) range of ∼70 % to ∼100 %, resulting in an organic-rich outer phase and a water-rich inner phase. These results may have implications for predicting the cloud nucleating properties of anthropogenic SOA since the presence of an organic-rich outer phase at high-RH values can lower the supersaturation with respect to water required for cloud droplet formation. At ≤10 % RH, the viscosity was ≥1×108 Pa s, which corresponds to roughly the viscosity of tar pitch. At 38 %–50 % RH, the viscosity was in the range of 1×108 to 3×105 Pa s. These measured viscosities are consistent with predictions based on oxygen to carbon elemental ratio (O:C) and molar mass as well as predictions based on the number of carbon, hydrogen, and oxygen atoms. Based on the measured viscosities and the Stokes–Einstein relation, at ≤10 % RH diffusion coefficients of organics within diesel fuel SOA is ≤5.4×10-17 cm2 s−1 and the mixing time of organics within 200 nm diesel fuel SOA particles (τmixing) is 50 h. These small diffusion coefficients and large mixing times may be important in laboratory experiments, where SOA is often generated and studied using low-RH conditions and on timescales of minutes to hours. At 38 %–50 % RH, the calculated organic diffusion coefficients are in the range of 5.4×10-17 to 1.8×10-13 cm2 s−1 and calculated τmixing values are in the range of ∼0.01 h to ∼50 h. These values provide important constraints for the physicochemical properties of anthropogenic SOA.

5G NR (New Radio) standard allows utilization of higher frequency spectrum into millimeter wave (mmWave) bands (24GHz to 71GHz and above) to support wider modulated signal bandwidths from 100MHz to more than 2GHz, higher data rate communication, and lower latency. RF chip design in mmWave frequency to support 5G NR has been realized to overcome many challenges in system integration, circuit design, process technology, and reliability. In this paper, we review the impact of Silicon process performance on mmWave front end transceiver solutions. A dual band (28GHz, 39GHz), multi-element transceiver SOC has been successfully integrated with antenna module and is ready for commercialization in 2019. [1]

In this letter, a family of power-normal probability density functions is proposed for the asymmetric non-Gaussian distribution of drain current. The results of the proposed methodology are compared against both statistical silicon data and SPICE model Monte Carlo simulation results. Excellent agreement is observed for the power-normal distribution with order of 2. With this proposed distribution, drain current at non-Gaussian high-sigma tail can be predicted by only median and variance extracted from statistical data of a small set of samples (e.g., 1 k). For the first time, a simple analytic model is presented to capture memory read current non-Gaussian tail distribution near -6σ or even beyond, which is a major challenge in memory design for 28 nm technology node and below.

Broad-band dielectric relaxation spectroscopy was used to investigate the molecular dynamics of reactive systems where one of the components exhibits, in addition to the transverse dipole moment component ( μ ⊥ or type B) that gives rise to the segmental α process, a persistent cumulative dipole moment along the chain contour ( μ ∥ or type A). The systems studied were composed of an amine-terminated poly(propylene oxide) (PPO), that contains type A and B dipoles, and a bifunctional epoxy prepolymer. The segmental and normal mode processes were clearly discernible in the neat PPO and the PPO/epoxy blends with PPO MW>2000 g/mol. The α process broadens upon mixing. The normal mode has a narrower spectrum than the segmental mode and is not affected by mixing. Cross-linking causes the segmental and normal modes to gradually overlap and we observe a deviation of the normal mode from the Rouse dynamics and a considerable broadening of the α process. The molecular architecture of the growing network plays an important role in determining the dynamics, as the compositional and spatial heterogeneities arise during cross-linking. Interestingly, while the increased heterogeneity results in the broadening of the relaxation spectra, the temperature dependence of the α process remains unaffected by cross-linking. This is a curious finding; the apparent lack of a direct correlation between non-exponentiality and fragility in cross-linking PPO networks may reflect the length scale of relaxation and warrants further investigation.

An investigation was carried out of the molecular dynamics of poly(l-lactic acid) before, during, and after crystallization. Experimental results were generated over a wide range of temperature and frequency by broad-band dielectric relaxation spectroscopy (DRS). An interesting finding is that the average relaxation time (defined as τ = 1/2πfmax, where fmax is the frequency at maximum loss for the α process) does not vary with degree of crystallinity during melt and/or cold crystallization. Moreover, the temperature dependence of the average relaxation time for wholly amorphous and crystallized samples is well-described by a single Vogel−Fulcher−Tammann (VFT) functional form. The unchanged fragility suggests that the segmental dynamics are not sensitive to the different degree of crystallinity, implying that the relaxing segments are smaller than the thickness of the amorphous layers between lamellae. Apparently, the distance between lamellae is greater than the length of the primitive segment and the cha...

A series of bis-phosphinite and bis-phosphite PONOP iron complexes were prepared and characterized by NMR and IR spectroscopy. Bis-phosphinite PONOP iron dichloride complexes (RPONOP)FeCl2 (RPONOP = 2,6-(R2PO)2(C5H3N) and R = iPr, tBu) were prepared through complexation of the free ligands with FeCl2 and their solid-state structures were determined. Bis-phosphite PONOP iron complexes (OEtPONOP)Fe(PMe3)2 and (CatPONOP)Fe(PMe3)2 (Cat = catechol) were synthesized through complexation of the free ligands to Fe(PMe3)4. Carbonyl complexes of both bis-phosphinite and bis-phosphite PONOP were prepared and characterized by IR. The monocarbonyl (iPrPONOP)Fe(CO)Cl2 was accessed through exposure of (iPrPONOP)FeCl2 to an atmosphere of CO and the CO stretching frequency was observed at 1969 cm-1. Dicarbonyl complexes (iPrPONOP)Fe(CO)2 and (OEtPONOP)Fe(CO)2 were accessed through reduction of the corresponding chloride complexes with sodium amalgam under a CO atmosphere. Carbonyl stretching frequencies for (iPrPONOP)Fe(CO)2 and (OEtPONOPFe)(CO)2 were observed at 1824 and 1876 cm-1, and at 1871 and 1927 cm-1 respectively. The bis-phosphite PONOP complexes exhibit a less electron rich metal center than the bis-phosphinite PONOP complexes, as would be expected based on the stronger π-acceptor character of these ligands. The electronic properties of the bis-phosphinite PONOP and bis-phosphite PONOP iron complexes are intermediate between previously reported PNP and PDI iron complexes, with the PONOP ligands exhibiting stronger electron donating ability than PDI ligands, but promoting a less electron rich metal center than found in analogous PNP iron complexes.

A liquid crystal monomer (LCM) was synthesized and attached as a side chain to a siloxane polymer (SCLCP). The molecular dynamics of LCM and SCLCP were investigated by broad-band dielectric relaxation spectroscopy (DRS) over 10 decades of frequency. The surface treatment of the electrodes was found to have a pronounced effect on the macroscopic alignment and dynamics. In the isotropic state the relaxations in LCM and SCLCP are well-described by the Kohlrausch−Williams−Watts (KWW) functional form. In the LC state, the overall dielectric response is a weighted sum of two dispersions that depend on the macroscopic alignment. The hometropic (H) alignment is dominated by the (slower) δ process, while the planar (P) alignment is dominated by the (faster) αm process. Both processes are symmetric and can be described by Cole−Cole (CC) or Fuoss−Kirkwood (FK) functional forms. The δ process governs the dynamics in the SCLCP near the glass transition, similar to the segmental α process in non-LC glass formers. Excel...

A comprehensive investigation of the reorientational dynamics of poly(vinylidene fluoride)/poly(methyl methacrylate) (PVDF/PMMA) blends was carried out. Dielectric relaxation spectroscopy (DRS) was performed over 11 decades of frequency and over a wide range of temperature on wholly amorphous, crystalline, and crystallizing blends of varying composition. The range of experimental conditions and compositional variables far exceeded those employed by previous investigators, enabling us to formulate a comprehensive view of the dynamics in these systems. A number of relaxation processes were detected, and their origins, temperature dependence, composition dependence, and spectral characteristics were established. Three α-type processes were observed: the αa process, associated with relaxations of all amorphous PVDF segments (not only within the crystalline−amorphous interphase); the αm process, which encompasses several relaxation processes and scales with blend composition; and the αc process, attributed to...

Dipole dynamics of a series of thermotropic liquid crystalline (LC) epoxy prepolymers and an LC epoxy/amine network were studied by broad-band dielectric relaxation spectroscopy (DRS) over a wide range of frequency and temperature. Two relaxation processes were observed in the prepolymers below the melting point: the β process, associated with the rotational motions of the LC rigid rods about their molecular axis, and the γ process, whose origin lies primarily in the localized motions of the terminal group. The α process, associated with the segmental motions, emerges as a low-intensity process above the calorimetric glass transition and quickly shifts into the gigahertz frequency range with increasing temperature. The δ process, associated with the end-over-end motions in the mesophase, is largely absent because of a negligible longitudinal dipole moment in these LC epoxy molecules. An in-situ investigation of the formation of an LC epoxy/amine network was conducted by DRS and polarized optical microsco...

The reorientational dynamics of dipoles in poly(vinylidene fluoride)/poly(methyl methacrylate) (PVDF/PMMA) blends were investigated by dielectric spectroscopy. Measurements were performed over a wide range of temperature and frequency, and previously unavailable results are reported. Various relaxation processes were identified and their locations assigned to the different morphological regions in PVDF, PMMA, and PVDF/PMMA blends. The development of a relaxation process associated with the imperfections in the crystalline phase was recorded both in pure PVDF and in crystalline blends. An amorphous interphase and a liquid-like amorphous phase are present in pure PVDF, but their relaxation dynamics are dielectrically indistinguishable, giving rise to a single non-Arrhenius relaxation mechanism. In the crystalline blends, however, the interphase is devoid of PMMA, and its relaxation dynamics are readily distinguishable from those of the PVDF/PMMA miscible phase. Interestingly, the relaxation dynamics in the ...