High Temperature Thermal Desorption Research Articles

Development of an ultra-clean sample heating stage for thermal desorption spectroscopy

Control of surface molecular contamination (SMC) for components used in chemical vapor deposition (CVD), atomic layer deposition (ALD) and EUV photolithography is important to maintaining high yield and optimal tool operation at the latest process nodes in leading edge semiconductor manufacturing. High temperature thermal desorption spectroscopy (TDS) is a versatile tool for analyzing the cleanliness of surfaces, simulating thermal vacuum processes and studying the kinetics of desorption processes. A basic analysis of TD spectra allows for full characterization of volatile outgassing from surfaces, while detailed analysis can provide chemical information about the substrate surface.In fundamental studies, TDS is often carried out from low temperatures to room temperature or for small samples. However, for microelectronics applications, high temperature studies of large (100 mm or greater) samples are of greater interest due to direct applications for cleanliness testing and thermal vacuum simulation. A limitation for TDS sensitivity is the outgassing of sample stage materials, particularly when analyzing gases that may be present in the chamber background such as water, CO and CO2. Typical sample stages are often tested only for total pressure or at room temperature.In this study, we present a simple ultra-high vacuum (UHV) compatible sample heating stage for trace outgassing analysis of 100 mm samples at high temperatures. Simulation results are presented to support the feasibility of the concept. Experimental results verify the cleanliness of the stage via room temperature residual gas analysis (RGA) analysis and X-ray photoelectron spectroscopy (XPS) of stage components. Finally, use of this stage in a TDS analysis of a 100 mm Si witness wafer and comparison to room temperature RGA demonstrates operational capability.The sample heating stage is both shown to be clean at high temperature and capable of analyzing 100 mm wafers to higher sensitivity than room temperature RGA for all m/z at the 1 × 10−9 mbar level. Despite its high performance, the heating stage is also easily produced by any laser machining service, greatly improving the accessibility of UHV science for all researchers.

Effects of thermal desorption on ecotoxicological characteristics of heavy petroleum-contaminated soil.

This study comprehensively evaluates the ecotoxicity of high-concentration heavy petroleum (HCHP)-contaminated soil before and after thermal desorption (TD) remediation at different temperatures and times. The results showed that the detoxification of contaminated soil was effectively achieved by extending the remediation duration at 400-600 °C. After treatment at 400 °C for 60 min, the toxicological indicators including bioluminescence EC50 (acute toxicity), seed germination ratio (Gr) and plant biomass of Brassica juncea (subacute toxicity), and diversity of the microbial community (chronic toxicity) reached a maximum. The value of the SOS-Induction Factor (SOSIF), characterizing genotoxicity was below 1.5, indicating that it was non-toxic. Pearson's correlation analysis illustrated that the water-soluble fraction (WSF), ALK1-3 and ARO1-3 of petroleum hydrocarbons were the primary sources of ecotoxicity. Notably, although the total ratio of petroleum removed from the soil reached 87.26 ± 4.38 %-98.69 ± 1.61 % under high-temperature thermal desorption (HTTD, 500-600 °C), the ecotoxicity was not lower than that at 400 °C. The pyrolysis products of petroleum macromolecules and extreme changes in soil properties were the leading causes of soil ecotoxicity following HTTD. The inconsistency between the removal of petroleum pollutants and ecological health risks reveals the significance of soil ecotoxicological assessments for identifying TD remediation endpoints and process optimization.

Changes in Soil Health with Remediation of Petroleum Hydrocarbon Contaminated Soils Using Two Different Remediation Technologies

For sustainable soil management, there is an increasing demand for soil quality, resilience, and health assessment. After remediation of petroleum hydrocarbon (PHC)-contaminated soils, changes in the physicochemical and ecological characteristics of the soil were investigated. Two kinds of remediation technologies were applied to contaminated soils: land farming (LF) and high temperature thermal desorption (HTTD). As a result of total petroleum hydrocarbons (TPH), PHC-contaminated soils were efficiently remediated by LF and HTTD. The soil health could not be completely recovered after the removal of pollutants due to adverse changes in the soil properties, especially in soil enzyme activities. Therefore, monitoring is necessary for accurate estimation of soil ecotoxicity and effective remediation, and additional soil management, such as fertilizer application or organic amendments, is needed to restore soil heath. In the case of HTTD, soil ecological properties are severely changed during the remediation process. The decision to reuse or recycle remediated soils should reflect changes in soil quality. HTTD is a harsh remediation method that results in deterioration of soil fertility and ecological functions. Alternatives, such as low-temperature thermal desorption or additional soil management using fertilizer or organic amendments, for example, are needed.

Helium and hydrogen interaction in tungsten simultaneously irradiated by He+-H2+ at high temperature

Tungsten (W) is one of the most promising candidates for plasma facing materials in the fusion reactor. Helium (He) in W can influence the retention of hydrogen isotopes. In the present study, W targets were simultaneously irradiated by He+-H2+ or He+-D2+ ion beams with the energies of 1 keV or 3 keV, at fixed temperatures in a range of room temperature (R.T.) to 1073 K. Mechanisms of He and hydrogen interaction in W were discussed, especially from the point of He retention, which was characterized by the high-temperature thermal desorption spectroscopy (TDS) and glow-discharge optical emission spectroscopy (GD-OES) measurements. It is found that He desorption shifts to a lower temperature range for the W simultaneously irradiated by 3 keV He+-1 keV H2+ at 573 K, under He+ fluence up to 1 × 1022 He+m−2. Transmission electron microscope (TEM) observation and annealing treatment at the temperature of 873–1073 K show that the increased He uptake is caused by the formation of dislocation. Enhanced retention amounts for the hydrogen isotopes were also confirmed. Amounts of the dislocation loops introduced by the H2+-only irradiation can be reduced by annealing treatment at 873 K, while that introduced by He+ irradiation are quite stable, which grows larger at elevated temperatures. With an increase of H2+ energy, Helium uptakes at both weak trapping sites and bubbles are increased, while the amounts of hydrogen retention are decreased. It suggests that hydrogen ion has a significant influence on the He trapping sites at the irradiation temperature up to 573 K, while the hydrogen retention is determined by the distribution of He bubbles and dislocation loops.

Insight into ex-situ thermal desorption of soils contaminated with petroleum via carbon number-based fraction approach

Ex-situ thermal desorption treatment (ESTD) of petroleum contaminated soil (PCS) was developed to investigate the desorption behavior of five carbon number-based fractions of extractable petroleum hydrocarbons (EPHs) and the morphology changes of soils. The experimental kinetics, isotherm models and thermodynamic parameters were analyzed to provide mechanism insight. Results suggest that most of the diesel range organics (DRO, C10-C28) was removed at low temperatures (100–350 °C), while high temperature (350–550 °C) thermal desorption (HTTD) was effective in removing EPHs due to the high removal efficiency of oil range organics (ORO, C28-C40). Under HTTD treatment, the re-adsorption of low molecular weight hydrocarbons was observed. The particle size of sandy soil barely changed during desorption process, while a significant agglomeration was found in red clayey at high temperatures. The desorption kinetics can be well fitted by the exponential decay model, and the desorption equilibrium agrees with the Langmuir isotherm model. The removal process of EPHs was controlled by multiple diffusion mechanisms. ΔH° values of GS and RS were 65.73 kJ/mol and 76.29 kJ/mol, respectively. DRO was mainly controlled by physical adsorption, while to a great extent ORO release was controlled by chemical adsorption. Finally, removal mechanisms and matrix control mechanisms during ESTD treatment were proposed.

Helium retention behavior in simultaneously He+-H2+ irradiated tungsten

The purpose of this study is to elucidate helium (He) retention behavior in tungsten (W) under simultaneous He and hydrogen (H) irradiation. Polycrystalline-W was irradiated by He+ and H2+ simultaneously with the energy of 1.0 keV and 3.0 keV. He+ fluences were (0.5, 1.0, 10) × 1021 He+ m−2 and H2+ fluence was 1.0 × 1022 H+ m−2,respectively. After irradiation, He desorption behavior was investigated by high temperature thermal desorption spectroscopy (HT-TDS) in the temperature range of R.T.-1773 K. Micro-structure changes of W after irradiation were observed by TEM. It was found that simultaneous irradiation with different H2+ energy significantly changed He retention behavior. 1.0 keV H2+ suppressed the He bubble growth and no bubbles can be observed at room temperature. On the other hand, 3.0 keV H2+ facilitated the formation of He bubbles and increased the He retention due to the additional damage introduction by energetic H2+.

Emulsion-templated fully three-dimensional interconnected porous titania ceramics with excellent humidity sensing properties

In this study, a facile emulsion templating method was developed for the preparation of high-performance monolithic porous titania-based humidity-sensing ceramics. High internal phase Pickering emulsions (HIPEs) with internal phase of 70vol%, stabilized by short-chain amphiphilic molecules in situ modified TiO2 solid nanoparticles, were employed as templates. The obtained sensors contain a hierarchically ordered three-dimensional interconnected pore structure and exhibit high sensitivity to water vapors as well as linear response in the wide relative humidity (RH) range between 11% and 95%. The observed sensor impedance variation can be as high as four orders of magnitude, depending on the RH value. In addition, the produced sensors are characterized by the reversible response with relatively small hysteresis and thus can be reversibly operated without repeated high-temperature thermal desorption cleaning.

Assessment of soil remediation technologies by comparing health risk reduction and potential impacts using unified index, disability-adjusted life years

The assessment methodology of soil remediation technologies including citizen’s opinions about environmental policy was developed to enable direct comparison between the resident health risk reduction by carrying out remediation (decreased primary risk) and the potential impacts of chemicals emitted during the remediation on national health, social assets, and primary production (secondary risk). Both risks were quantified with an unified index, disability-adjusted life years (DALYs), by employing life cycle costing (LCC), economic input–output life cycle assessment (EIO-LCA), and life cycle impact assessment (LCIA) database. Four remediation technologies were considered: excavation–disposal, high temperature thermal desorption (HTTD), biopile, and landfarming. There was almost no difference in the decreased primary risk among the four technologies, apart from landfarming, which had the smallest decreased primary risk. The secondary risk of the biological technologies (biopile, landfarming) was smaller than that of the physical and chemical technologies (excavation–disposal, HTTD). The ratio of the decreased primary risk to the secondary risk was largest in case of landfarming, which indicated that landfarming was most effective. The sum of the residual primary risks and secondary risk was small in the biological technologies, indicating that the biological technologies had smaller environmental impacts. Indexing both of decreased primary risk and secondary risk with DALYs enables non-experts who prioritize resident’s health to assess the soil remediation technologies and would facilitate the decision making in the selection of remediation technologies.

<i>Situ</i> Remediation of Heavy Metal Contaminated Sites

Remediation of heavy metal contaminated sites is the important part in environmental governance. In this paper, based on the study of heavy metal pollution situation and soil characteristics in Shanxi Province, we analyse various typical technology of heavy metal contaminated site remediation. Put forward the suitable method for heavy metal remediation, mainly include: Solidification / stabilization, nanozero valent iron-situ remediation technologies, leaching, chemical extraction, low temperature thermal desorption, high temperature thermal desorption, phytoremediation.

Assessment of soil screening levels due to ingestion and dermal absorption of chrysene and benzo[k]fluoranthene and appropriate remediation method for Dorson Abad

For years, the Dorson Abad region has been extremely polluted by Tehran Oil Refinery due to leaking from its underground pipelines, storage tanks, and evaporation ponds. To assess the concentrations of hazardous polycyclic aromatic hydrocarbon (PAH) compounds, soil samples were collected from the grounds at and adjacent to a polluted stream located in the study area. The samples were then analyzed, and the results revealed that 12 of the 16 USEPA PAHs were noticeably present in the soil, which, among them, benzo[k]fluoranthene and chrysene had the highest concentrations with averages of 357.17 and 173.38 mg/kg, respectively. A comparison of the obtained concentrations with the soil screening levels indicated that both benzo[k]fluoranthene and chrysene concentrations were substantially higher than EPA screening level values, signifying the necessity of soil remediation for these contaminants in the area. Techniques such as soil washing/flushing, high temperature thermal desorption, and solidification/stabilization were investigated for treatment of the contaminated soil; solidification/stabilization is recommended as an applicable and cost-effective remediation method for Dorson Abad due to the size of the region, relatively low cost of the binder (cement), and low volatility of benzo[k]fluoranthene and chrysene.

Surficial Chemical States of Li<sub>3</sub>N Synthesized on Lithium Target for Boron Neutron Capture Therapy

To remove high level of contaminants by O and C from Li3N surface for Boron Neutron Capture Therapy target, high temperature thermal desorption was conducted up to 1123 K in ultra high vacuum and the following results were derived; During thermal desorption up to 1023 K, typical three peaks of vacuum pressure disturbance due to vaporization of contaminants were observed in vacuum pressure-temperature curve. Over-layered contaminants with high melting temperature below 1023 K on Li3N surface is completely removed by high temperature thermal desorption up to 1123 K in ultra high vacuum. From these desorption results, it is suggested that these contaminants corresponding to these vaporization peaks are H2O and Li compounds with high melting temperature below 1023 K, of which LiOH and Li2CO3 were synthesized by decomposition process of Li3N with residual H2O and CO2 in low temperature.

ホウ素中性子捕獲療法のためのリチウムターゲット表面に合成した Li<sub>3</sub>N の表面化学状態

To remove high level of contaminants by O and C from Li3N surface for Boron Neutron Capture Therapy target, high temperature thermal desorption was conducted up to 1123 K in ultra high vacuum and the following results were derived; (1) During thermal desorption up to 1023 K, typical three peaks of vacuum pressure disturbance due to vaporization of contaminants were observed in vacuum pressure-temperature curve. (2) Over-layered contaminants having lower melting point than 1023 K on Li3N surface is completely removed by high temperature thermal desorption up to 1123 K in ultra high vacuum. (3) From these desorption results, it is suggested that these contaminants corresponding to these vaporization peaks are H2O and Li compounds having lower melting point than 1023 K, of which LiOH and Li2CO3 were synthesized by decomposition process of Li3N with residual H2O and CO2 in low temperature.

A Study on the Operation Parameter for Treatment of Carcass Burial Leachate in High Temperature Thermal Desorption

A Study on the Operation Parameter for Treatment of Carcass Burial Leachate in High Temperature Thermal Desorption

고온 열탈착 시설을 이용한 가축 매몰지 침출수 처리를 위한 유해물질 특성분석연구

고온 열탈착 시설을 이용한 가축 매몰지 침출수 처리를 위한 유해물질 특성분석연구

Two-scale evaluation of remediation technologies for a contaminated site by applying economic input–output life cycle assessment: Risk–cost, risk–energy consumption and risk–CO 2 emission

A two-scale evaluation concept of remediation technologies for a contaminated site was expanded by introducing life cycle costing (LCC) and economic input–output life cycle assessment (EIO-LCA). The expanded evaluation index, the rescue number for soil ( RN SOIL ) with LCC and EIO-LCA, comprises two scales, such as risk–cost, risk–energy consumption or risk–CO 2 emission of a remediation. The effectiveness of RN SOIL with LCC and EIO-LCA was examined in a typical contamination and remediation scenario in which dieldrin contaminated an agricultural field. Remediation was simulated using four technologies: disposal, high temperature thermal desorption, biopile and landfarming. Energy consumption and CO 2 emission were determined from a life cycle inventory analysis using monetary-based intensity based on an input–output table. The values of RN SOIL based on risk–cost, risk–energy consumption and risk–CO 2 emission were calculated, and then rankings of the candidates were compiled according to RN SOIL values. A comparison between three rankings showed the different ranking orders. The existence of differences in ranking order indicates that the scales would not have reciprocal compatibility for two-scale evaluation and that each scale should be used independently. The RN SOIL with LCA will be helpful in selecting a technology, provided an appropriate scale is determined.

Oxygen desorption from polycrystalline palladium: Thermal desorption of O2 from a chemisorbed layer of Oads in the course of the decomposition of PdO surface oxide and in the release of oxygen from the bulk of palladium

The desorption of oxygen from polycrystalline palladium (Pd(poly)) was studied using temperature-programmed desorption (TPD) at 500–1300 K and the amounts of oxygen absorbed by palladium (n) from 0.05 to 50 monolayers. It was found that the desorption of O2 from Pd(poly), which occurred from a chemisorbed oxygen layer (Oads), in the release of oxygen from a near-surface metal layer in the course of the decomposition of PdO surface oxide, and in the release of oxygen from the bulk of palladium (Oabs), was governed by repulsive interactions between Oads atoms and the formation and decomposition of Oads-Pd*-Oabs structures (Pd* is a surface palladium atom). At θ ≤ 0.5, the repulsive interactions between Oads atoms (ɛaa = 10 kJ/mol) resulted in the desorption of O2 from Pd(poly) at 650–950 K. At 0.5 ≤ n ≤ 1.0, the release of inserted oxygen from a near-surface palladium layer occurred during TPD in the course of the migration of Oabs atoms to the surface and the formation-decomposition of Oads-Pd*-Oabs structures. As a result, the desorption of O2 occurred in accordance with a first-order reaction with a thermal desorption (TD) peak at Tmax ∼ 700 K. At 1.0 ≤ n ≤ 2.0, the decomposition of PdO surface oxide occurred at a constant surface cover-age with oxygen during TPD in the course of the formation-decomposition of Oads-Pd*-Oabs structures. Because of this, the desorption of O2 occurred in accordance with a zero-order reaction at low temperatures with a TD peak at Tmax ∼ 675 K. At 1.0 ≤ n ≤ 50, oxygen atoms diffused from deep palladium layers in the course of TPD and arrived at the surface at high temperatures. As a result, O2 was desorbed with a high-temperature TD peak at T > 750 K.

Low temperature headspace desorption of volatile organic compounds trapped in air sampling solid-supports

Environmental context. The monitoring of volatile organic compounds (VOCs) in air is of great importance for air quality on both local and global scales. The determination of VOCs can be carried out by gas chromatography–mass spectrometry (GC-MS) after active or passive sampling and (high temperature) thermal desorption. An attractive alternative would be to combine GC-MS with headspace (HS) systems as it allows simpler, faster, low temperature desorption. We present here the first report of HS-GC-MS for the determination of VOCs in air sampled using solid supports. Abstract. The use of a headspace (HS) for low temperature desorption of VOCs, previously sorbed from indoor air on solid supports, has been evaluated in order to improve the GC-MS determinations in environmental studies. Graphitised carbon black (GCB), Porapak and Tenax were considered in this study. The HS injector does not allow temperatures higher than 150°C, so there is no a complete desorption of VOCs. However highly volatile compounds were completely desorbed from Porapak and Tenax, but compounds of low volatility showed a strong retention with recoveries of 71–100% for Porapak and 59–100% for Tenax. All studied VOCs were quantitatively desorbed from GCB. Only 100 μL of the HS volume is injected in the chromatographic system. So in spite of the reduced sensitivity we are able to make replicate analyses on the same sampler. Additional experiments were performed using the proposed methodology for the analysis of aforementioned supports in passive and active sampling modes. In short, the proposed methodology reduces the energy consumed and makes it possible to determine the VOCs in air with reduced cost media. The developed methodology permits the determination of 32 VOCs with limits of detection values around 1 μg m–3 when actively sampling air at 50 mL min–1 for 2 h and using 100 mg solid sorbent.

Interaction between oxygen and polycrystalline palladium at O2 pressures of 10−6–10 Pa

The interaction between oxygen and polycrystalline palladium (Pd(poly)) at \( P_{O_2 } \) = 2.6 × 10−6–10 Pa and T = 300–1300 K was studied by the thermal desorption (TD) method. The interaction between O2 and Pd(poly) is governed by the O2 pressure and the sample temperature. At low pressures of \( P_{O_2 } \) (≤1.3 × 10−5 Pa), O2 is chemisorbed dissociatively on the Pd(poly) surface. During chemisorption, the Oads-surface bond energy and the O2 sticking coefficient gradually decrease as the surface coverage θ increases. At \( P_{O_2 } \) ≥ 10−2 Pa and T ≤ 500 K, after the saturation of the Oads layer (θ ∼ 0.5), Oads atoms penetrate under the surface layer of the metal to form surface palladium oxide. At \( P_{O_2 } \) ≥ 1 Pa and T > 500 K, after the saturation of the surface oxide film 2 ML in thickness (n ∼ 2), Oads atoms penetrate into the oxide film and then into the subsurface palladium layer and diffuse deep into the metal bulk. As a result, the oxygen uptake at 700 K is n ∼ 50. Upon heating, the surface oxides decompose, desorbing O2, which gives rise to a low-temperature TD peak with Tmax = 715 K. The release of oxygen inserted in the subsurface layers of palladium shows itself as a distinct high-temperature TD peak with Tmax ≥ 750 K.

Retrospective identification of chemical warfare agents by high-temperature automatic thermal desorption–gas chromatography–mass spectrometry

An automated thermal desorption (ATD)–gas chromatography–mass spectrometry method was developed for the analysis of selected chemical warfare (CW) agents. Suitable methods were developed for analytes of high volatility to low volatility. The less volatile CW agents required the purchase and installation of a high-temperature valve upgrade kit allowing valve temperatures of up to 260°C to be reached. The limit of detection was 50 ng on the tube for most CW agents in full scan. Chloropicrin exhibited some temperature dependence, with detection limits improving as ATD temperatures were decreased below 150°C. A sample storage trial was undertaken to establish the most suitable storage environment for CW agents adsorbed onto Tenax TA. Temperature and time of storage were found to influence recovery of analytes with best recoveries being observed after 1 day storage in a freezer (−12°C). This method was evaluated during a trial of procedures for sampling and identification of chemical agents at Porton Down, UK. Sulfur mustard was detected downwind of a simulated exploded munition.

Analysis of volatile radiolysis products in gamma-irradiated LDPE and polypropylene films by thermal desorption–gas chromatography–mass spectrometry

Low-molecular-weight (‘volatile’) radiolysis products of low-density polyethylene (LDPE) and polypropylene (PP) films were investigated by thermal desorption–(TDS)–GC–MS after absorbed doses of up to 25 kGy. The films produce fingerprint chromatograms with highly characteristic patterns of groups of radiation-induced peaks; these are mainly hydrocarbons, aldehydes, ketones, and carboxylic acids with concentrations (after 25 kGy) ca one order of magnitude below that of the residual hydrocarbons (oligomers). PP additionally produces very substantial amounts of three degradation products of phenol-type antioxidants. The low molecular-weight (MW) radiolysis products are retained for considerable times in LDPE films and they are retained in PP films much longer than had been expected. Besides product identification, the following topics are addressed: Effects of the absorbed dose and the desorption temperature; comparison of several commercial (proprietary) films; high-temperature thermal desorption; the question whether TDS analyzes radiation-induced artifacts rather than genuine products; the possible existence of cyclic radiolysis products; the possibility of identifying an LDPE film as irradiated after a dose of only 1 kGy; and atypical trace fragments of antioxidants. Finally, the geometry and efficiency of the thermal desorption system is briefly discussed, and the implications of our findings for irradiation detection and for the safety of irradiated materials are considered.