采用热电离质谱法(thermal ionization mass spectrometry,TIMS)测定铀同位素过程中,质量分馏效应会引起同位素比值测量值偏离真值,一般采用外标校正法对质量分馏效应进行校正,这要求测量过程中标准物质和样品产生一致的质量分馏行为。...采用热电离质谱法(thermal ionization mass spectrometry,TIMS)测定铀同位素过程中,质量分馏效应会引起同位素比值测量值偏离真值,一般采用外标校正法对质量分馏效应进行校正,这要求测量过程中标准物质和样品产生一致的质量分馏行为。因此,除考虑点样的一致性外,测量过程中产生单一的目标离子也非常重要。本研究采用热电离质谱技术考察了铼灯丝氧化对铀同位素测定的影响。将1μg铀以硝酸盐溶液的形式点于铼样品带上,通过监测铀及其氧化物的离子流强度,发现铀主要存在U+和UOx+(x=1或2)的电离形态,并且灯丝表面氧化程度越高,UOx+的产率越高(UOx+/U+可达到1)。实验结果表明,灯丝去气过程过早使灯丝暴露于大气或点样过程中,以及使用较高的样品蒸干电流都会加剧灯丝的氧化。控制灯丝表面氧化或点样过程中加入石墨,可有效降低UOx+的产率,提高目标离子的电离效率。全蒸发测量结果表明,UOx+离子流强度大小对测量结果无明显影响,但通过降低UOx+的离子流强度,可提高测量结果的重现性,进而提高测量过程中分馏行为的一致性。该研究可为提高铀同位素测定过程中样品的利用率提供理论依据。展开更多
对影响热电离质谱全蒸发测量的主要因素进行研究,包括点样量、同质异位素的干扰等,并将全蒸发技术与传统测量技术测量IRMM-086的结果进行对比。结果表明,全蒸发技术可在更少的点样量下获得比传统测量法更佳的测量精度,当同位素比值大于1...对影响热电离质谱全蒸发测量的主要因素进行研究,包括点样量、同质异位素的干扰等,并将全蒸发技术与传统测量技术测量IRMM-086的结果进行对比。结果表明,全蒸发技术可在更少的点样量下获得比传统测量法更佳的测量精度,当同位素比值大于10-4时,结果与标准值偏差小于2σ。在50 ng IRMM-086点样量下,全蒸发测量的^(240)Pu/^(239)Pu、^(241)Pu/^(239)Pu、^(242)Pu/^(239)Pu相对标准偏差分别为0.0068%、0.50%和0.83%。对于钚同位素比值分析,全蒸发测量技术可直接获得高精度、高准确度的测量结果。展开更多
Comparing with the coordinates measuring machine (CMM),the theodolite industrial measuring system (TIMS) can be easily moved and it can measure large sized industrial targets contactlessly.But up to now the precision...Comparing with the coordinates measuring machine (CMM),the theodolite industrial measuring system (TIMS) can be easily moved and it can measure large sized industrial targets contactlessly.But up to now the precision of the TIMS has been considered so low that the TIMS isnt applied to some precise measurements.The error in self locating TIMS is a main factor which affects the precision of the TIMS.A new model of the TIMS is given out in this paper,and it can eliminate the error in self locating the TIMS.The new model is not only investigated and analyzed theoretically but also verified by the real measured data.展开更多
Two national stalagmite standard （GBW04412, GBW04413） and one international coral standard （RKM4） have been determined by using thermal ionization mass spectrometry （TIMS） method. The values of （ 234 U/ 238 U）...Two national stalagmite standard （GBW04412, GBW04413） and one international coral standard （RKM4） have been determined by using thermal ionization mass spectrometry （TIMS） method. The values of （ 234 U/ 238 U） act , （ 230 Th/ 234 U） act and age are all consistent in error range with the standard values obtained by using α spectrometry.展开更多
Dating techniques including gypsum dissolution in water, iron hydroxide co-precipitation with uranium and thorium and mass spectrometric determination have been investigated in this note. The ages of the gypsum sample...Dating techniques including gypsum dissolution in water, iron hydroxide co-precipitation with uranium and thorium and mass spectrometric determination have been investigated in this note. The ages of the gypsum samples in a CK core from Luobubo lacustrine sediments are in the range of (12.85±0.21) kaBP (4 m distance from the top core) to (153.2 ± 7.2) kaBP (49 m distance from the top core) with the relative errors of ( 1.6%-±4.7%. It indicates that the sedimental environment of the CK core was situated in the middle-late Pleistocene and Holocene periods, corresponding to 1-6 stages of oxygen isotopes in the abyssal sediments and included much information from last inter-glacial to Holocene warm periods.展开更多
Vertically aligned carbon nanotubes arrays(VACNTs)are a promising candidate for the thermal interface material(TIM)of next-generation electronic devices due to their attractive thermal and mechanical properties.Howeve...Vertically aligned carbon nanotubes arrays(VACNTs)are a promising candidate for the thermal interface material(TIM)of next-generation electronic devices due to their attractive thermal and mechanical properties.However,the environment required for synthesizing VACNTs is harsh and severely incompatible with standard device packaging processes.VACNTs’extremely low in-plane thermal conductivity also limits its performance for cooling hot spots.Here,using a transfer-and-encapsulate strategy,a two-step soldering method is developed to cap both ends of the VACNTs with copper microfoils,forming a standalone Cu-VACNTs-Cu sandwich TIM and avoiding the need to directly grow VACNTs on chip die.This new TIM is fully compatible with standard packaging,with excellent flexibility and high thermal conductivities in both in-plane and through-plane directions.The mechanical compliance behavior and mechanism,which are critical for TIM applications,are investigated in depth using in situ nanoindentation.The thermal performance is further verified in an actual light emitting diode(LED)cooling experiment,demonstrating low thermal resistance,good reliability,and achieving a 17℃ temperature reduction compared with state-of-the-art commercial TIMs.This study provides a viable solution to VACNTs’longstanding problem in device integration and free-end contact resistance,bringing it much closer to application and solving the critical thermal bottleneck in next-generation electronics.展开更多
文摘采用热电离质谱法(thermal ionization mass spectrometry,TIMS)测定铀同位素过程中,质量分馏效应会引起同位素比值测量值偏离真值,一般采用外标校正法对质量分馏效应进行校正,这要求测量过程中标准物质和样品产生一致的质量分馏行为。因此,除考虑点样的一致性外,测量过程中产生单一的目标离子也非常重要。本研究采用热电离质谱技术考察了铼灯丝氧化对铀同位素测定的影响。将1μg铀以硝酸盐溶液的形式点于铼样品带上,通过监测铀及其氧化物的离子流强度,发现铀主要存在U+和UOx+(x=1或2)的电离形态,并且灯丝表面氧化程度越高,UOx+的产率越高(UOx+/U+可达到1)。实验结果表明,灯丝去气过程过早使灯丝暴露于大气或点样过程中,以及使用较高的样品蒸干电流都会加剧灯丝的氧化。控制灯丝表面氧化或点样过程中加入石墨,可有效降低UOx+的产率,提高目标离子的电离效率。全蒸发测量结果表明,UOx+离子流强度大小对测量结果无明显影响,但通过降低UOx+的离子流强度,可提高测量结果的重现性,进而提高测量过程中分馏行为的一致性。该研究可为提高铀同位素测定过程中样品的利用率提供理论依据。
文摘对影响热电离质谱全蒸发测量的主要因素进行研究,包括点样量、同质异位素的干扰等,并将全蒸发技术与传统测量技术测量IRMM-086的结果进行对比。结果表明,全蒸发技术可在更少的点样量下获得比传统测量法更佳的测量精度,当同位素比值大于10-4时,结果与标准值偏差小于2σ。在50 ng IRMM-086点样量下,全蒸发测量的^(240)Pu/^(239)Pu、^(241)Pu/^(239)Pu、^(242)Pu/^(239)Pu相对标准偏差分别为0.0068%、0.50%和0.83%。对于钚同位素比值分析,全蒸发测量技术可直接获得高精度、高准确度的测量结果。
文摘Comparing with the coordinates measuring machine (CMM),the theodolite industrial measuring system (TIMS) can be easily moved and it can measure large sized industrial targets contactlessly.But up to now the precision of the TIMS has been considered so low that the TIMS isnt applied to some precise measurements.The error in self locating TIMS is a main factor which affects the precision of the TIMS.A new model of the TIMS is given out in this paper,and it can eliminate the error in self locating the TIMS.The new model is not only investigated and analyzed theoretically but also verified by the real measured data.
文摘Two national stalagmite standard （GBW04412, GBW04413） and one international coral standard （RKM4） have been determined by using thermal ionization mass spectrometry （TIMS） method. The values of （ 234 U/ 238 U） act , （ 230 Th/ 234 U） act and age are all consistent in error range with the standard values obtained by using α spectrometry.
基金This work was supported by the National Key Basis Research Project (Grant No. G19990434) the Innovative Project of the Chinese Academy of Sciences (Grant No. KZCX 1-y 05) and the Resources and Environment Basis Project of the University of Science an
文摘Dating techniques including gypsum dissolution in water, iron hydroxide co-precipitation with uranium and thorium and mass spectrometric determination have been investigated in this note. The ages of the gypsum samples in a CK core from Luobubo lacustrine sediments are in the range of (12.85±0.21) kaBP (4 m distance from the top core) to (153.2 ± 7.2) kaBP (49 m distance from the top core) with the relative errors of ( 1.6%-±4.7%. It indicates that the sedimental environment of the CK core was situated in the middle-late Pleistocene and Holocene periods, corresponding to 1-6 stages of oxygen isotopes in the abyssal sediments and included much information from last inter-glacial to Holocene warm periods.
基金supported by the National Natural Science Foundation of China(No.52076041)the Natural Science Foundation of Jiangsu Province(No.BK20200371)the Nanjing Carbon Peak and Carbon Neutrality Science and Technology Innovation Project(No.202211009)。
文摘Vertically aligned carbon nanotubes arrays(VACNTs)are a promising candidate for the thermal interface material(TIM)of next-generation electronic devices due to their attractive thermal and mechanical properties.However,the environment required for synthesizing VACNTs is harsh and severely incompatible with standard device packaging processes.VACNTs’extremely low in-plane thermal conductivity also limits its performance for cooling hot spots.Here,using a transfer-and-encapsulate strategy,a two-step soldering method is developed to cap both ends of the VACNTs with copper microfoils,forming a standalone Cu-VACNTs-Cu sandwich TIM and avoiding the need to directly grow VACNTs on chip die.This new TIM is fully compatible with standard packaging,with excellent flexibility and high thermal conductivities in both in-plane and through-plane directions.The mechanical compliance behavior and mechanism,which are critical for TIM applications,are investigated in depth using in situ nanoindentation.The thermal performance is further verified in an actual light emitting diode(LED)cooling experiment,demonstrating low thermal resistance,good reliability,and achieving a 17℃ temperature reduction compared with state-of-the-art commercial TIMs.This study provides a viable solution to VACNTs’longstanding problem in device integration and free-end contact resistance,bringing it much closer to application and solving the critical thermal bottleneck in next-generation electronics.
