CN107037112A

CN107037112A - A kind of Ne gas isotope measure method

Info

Publication number: CN107037112A
Application number: CN201610882463.4A
Authority: CN
Inventors: 苏菲; 贺怀宇
Original assignee: Institute of Geology and Geophysics of CAS
Current assignee: Institute of Geology and Geophysics of CAS
Priority date: 2016-10-10
Filing date: 2016-10-10
Publication date: 2017-08-11
Anticipated expiration: 2036-10-10
Also published as: CN107037112B

Abstract

The invention belongs to isotope measure field, and in particular to a kind of Ne gas isotope measure method.Methods described is to measure multiple calibration samples using mass spectrograph to obtain⁴⁰Ar⁺⁺With⁴⁰Ar⁺Relational expression, then measure testing sample⁴⁰Ar⁺, removed by calculating in testing sample⁴⁰Ar⁺⁺To testing sample at mass number 20²⁰Ne influence realizes that testing sample Ne gas isotopes are accurately measured；Measurement parameter of the mass spectrograph when measuring the multiple calibration sample with the testing sample is identical；The multiple calibration sample is free of Ne elements；The Ar contents of each the multiple calibration sample are different.

Description

A kind of Ne gas isotope measure method

Technical field

The invention belongs to isotope measure field, and in particular to a kind of Ne gas isotope measure method.

Background technology

Ne isotopic contents and its ratio are applied than wide in geoscience, for sample outside ground, such as aerolite, Ne Isotope can be used to calculate its universe Exposure Ages, and for earth mantle sample, such as mantle peridotite, Ne isotopes can be for judgement Constituent of atomsphere, isotope fractionation and differentiation MORB and OIB source regions in sample, for mineral deposit sample, such as pyrite, the same positions of Ne Element can for spike BIFhosted gold deposit source.

Ne has three isotopes,²⁰Ne,²¹Ne and²²Ne, wherein²¹Ne and²²Disturb small at Ne peak positions and be easier to remove Interference, measurement difficulty is little, but²⁰It is highly susceptible at Ne⁴⁰Ar⁺⁺Influence, and⁴⁰Ar⁺⁺Influence be not easy remove, therefore²⁰Ne accurate measurement difficulty is larger.Will²⁰Ne and⁴⁰Ar⁺⁺Mass spectrographic resolution ratio is separately needed to reach more than 1200, prior art In rare gas mass spectrograph mass resolution can not all reach, so measure Ne when⁴⁰Ar⁺⁺Presence will influence measurement²⁰Ne accuracy.

Usually, using mass spectrum mass resolving power (MRP, mass resolution power), using in peak The heart does the mode offset, looks for as far as possible²⁰Smooth position is tried one's best in Ne peak position to measure.For example, generally mass spectrograph is done certainly Dynamic peak center can be⁴⁰Ar⁺⁺With²⁰In Ne superposition peak position, then oneself calculates and is displaced to²⁰Need skew many in Ne peak position Few mass number, Input Offset Value namely determines peak position measurement manually in process of measurement.

The measurement Ne of current this peak center skew method, be only applicable to the higher situation of Ne semaphores (> 50000cps, is approximately higher than 7 × 10^-12CcSTP), preferably, Ar disturbs relatively low situation to the purification effect that is particularly suitable for use in, i.e.,²⁰Ne/⁴⁰Ar⁺⁺Higher situation, generally²⁰Ne/⁴⁰Ar⁺⁺>Could accurately it be measured when 5.But work as²⁰Ne semaphore is less than 7 × 10^-12ccSTP When, just can not accurately it measure²⁰Ne。

The content of the invention

In view of the above-mentioned problems, the invention provides a kind of Ne gas isotope measure method, the measuring method is to measurement sample The limitation of signal content it is smaller, it is not single can measure the higher situation of Ne semaphores (>50000cps, i.e. content are approximately higher than 7 × 10^- ¹²CcSTP), at the same can accurately measure low Ne contents (²⁰Ne semaphore<5000cps, i.e. content are less than about 7 × 10^- ¹²During ccSTP) the Ne gas isotopes of sample.

The present invention is achieved by the following technical solutions：

A kind of Ne gas isotope measure method, methods described is to measure multiple calibration samples using mass spectrograph to obtain⁴⁰Ar⁺⁺ With⁴⁰Ar⁺Relational expression, then measure testing sample⁴⁰Ar⁺, removed by calculating in testing sample⁴⁰Ar⁺⁺At mass number 20 pair Testing sample²⁰Ne influence realizes that testing sample Ne gas isotopes are accurately measured；The mass spectrograph is measuring the multiple calibration Measurement parameter when sample is with the testing sample is identical；The multiple calibration sample is free of Ne elements；Each the multiple calibration The Ar contents of sample are different.⁴⁰Ar⁺⁺With⁴⁰Ar⁺Relational expression can be different because of different instrument different parameters, but for same Under the conditions of one instrument identical parameters, the relation is stable.

Further, methods described specifically includes following steps：

(1) multiple calibration samples are measured using mass spectrograph⁴⁰Ar⁺With⁴⁰Ar⁺⁺Obtained according to measurement result fitting⁴⁰Ar⁺⁺ With⁴⁰Ar⁺Relational expression；

(2) with mass spectrograph measure testing sample mass number 20 (²⁰Ne and⁴⁰Ar⁺⁺Be superimposed peak at) place and⁴⁰Ar⁺Obtain treating test sample The mass 20 of product and testing sample⁴⁰Ar⁺Value；

(3) according to described⁴⁰Ar⁺⁺With⁴⁰Ar⁺Relational expression and the testing sample⁴⁰Ar⁺Value calculate obtain sample to be measured Product⁴⁰Ar⁺⁺；

(4) testing sample²⁰Testing sample described in the mass 20- of Ne value=testing sample⁴⁰Ar⁺⁺。

Further, during the mass spectrograph measurement testing sample, the mass spectrograph and the activated carbon cold-trap under liquid nitrogen temperature Be connected the Ar not removed with adsorption and purification system with 70-90K cold pump.

Further, the Ar of the multiple calibration sample semaphore scope is 300cps~100000cps.The Ar letters Number bigger fitting data of excursion is more accurate

Further, the number of the multiple calibration sample is more than 5.Calibration sample is more, and fitting data amount to be intended Close what is obtained⁴⁰Ar⁺⁺With⁴⁰Ar⁺Relational expression it is more accurate.

Further, the measurement parameter includes being primarily referred to as mass ion source and receiver is my parameter；During work, adjust After whole good measurement parameter, it is stored in some tuning file, is all called when surveying calibration sample and testing sample same Tuning files；The mass ion source includes high pressure, ion trap electric current, ion trap voltage, filament voltage；It is described to receive Device includes electron multiplier high pressure.

Further, the testing sample²⁰Ne semaphores are less than about 7 × 10 less than 50000cps, i.e. content^-11ccSTP。

Further, the testing sample²⁰Ne semaphores are less than 7 × 10 less than 5000cps, i.e. content^-12ccSTP。

The advantageous effects of the present invention：

(1) requirement reduction of the present invention to testing sample：The Ne of prior art measuring method can only be directed to²⁰Ne signals Amount is approximately higher than 7 × 10 more than 50000cps, i.e. content^-11CcSTP sample, and²⁰Ne/⁴⁰Ar⁺⁺>The measurement situation of 5 sample compared with It is good, the method measurement Ne isotopes that the present invention is corrected using Ar, for²⁰Ne semaphores are less than about 7 less than 50000cps, i.e. content ×10^-11CcSTP, or even semaphore are less than 7 × 10 less than 5000cps, i.e. content^-12CcSTP can be measured more accurately.

(2) present invention avoids determining peak position measurement manually in the prior art, and reduction error, precision are high.

(3) the inventive method is simple, easy, and exploitativeness is high.

Brief description of the drawings

Peak figure at Fig. 1, in the prior art measurement mass20；

In Fig. 2, the embodiment of the present invention⁴⁰Ar⁺⁺With⁴⁰Ar⁺Relational expression fitting schematic diagram；

Fig. 3, measurement result of the embodiment of the present invention and traditional measurement comparative result figure.

Embodiment

In order to make the purpose , technical scheme and advantage of the present invention be clearer, it is right below in conjunction with drawings and Examples The present invention is explained in further detail.It should be appreciated that specific embodiment described herein is used only for explaining the present invention, and It is not used in the restriction present invention.

On the contrary, the present invention covers any replacement done in the spirit and scope of the present invention being defined by the claims, repaiied Change, equivalent method and scheme.Further, in order that the public has a better understanding to the present invention, below to the thin of the present invention It is detailed to describe some specific detail sections in section description.Part without these details for a person skilled in the art Description can also understand the present invention completely.

Embodiment 1

In the prior art, as shown in figure 1, transverse axis is mass number, the longitudinal axis is semaphore, unit be count each second (cps, count per second).Will²⁰Ne and⁴⁰Ar⁺⁺Mass spectrographic resolution ratio will reach more than 1200 if separating, current main flow Rare gas mass spectrograph mass resolution can not all reach, so when measuring Ne⁴⁰Ar⁺⁺Presence will influence measurement²⁰Ne's Accuracy.

The present invention is using correction⁴⁰Ar⁺⁺Method measure²⁰Ne, with the application on Nobleese rare gas mass spectrographs Exemplified by, measuring method comprises the following steps：

(1) mass spectrograph 11 calibration samples of measurement are utilized⁴⁰Ar⁺With⁴⁰Ar⁺⁺Obtained according to measurement result fitting⁴⁰Ar⁺⁺ With⁴⁰Ar⁺Relational expression：⁴⁰Ar⁺⁺=0.2316*⁴⁰Ar⁺-1.2813；The calibration sample of selection⁴⁰Ar semaphore is in 400- Between 18700cps, as shown in Figure 2.

(4) testing sample²⁰Testing sample described in the mass 20- of Ne value=testing sample⁴⁰Ar⁺⁺.Measure²⁰Ne semaphore is from 2000cps to 16000cps.The contrast for being different from traditional measurement method is as shown in Figure 3.This patent side Method is effectively reduced²⁰Ne/²²The fluctuation of Ne ratios.

Wherein measurement parameter is respectively：Source parameters：High pressure：6000V, ion trap electric current：350 microamperes, ion trap electricity Pressure：25V, filament voltage：- 84V, receiver is risen using electron multiplication, and its high pressure is 2540V.

Above-mentioned Ne isotope measures method can be applied to various aspects, for sample outside ground, such as aerolite, and Ne isotopes can For calculating its universe Exposure Ages, for earth mantle sample, such as mantle peridotite, Ne isotopes can be for big in judgement sample Gas component, isotope fractionation and differentiation MORB and OIB source regions, for mineral deposit sample, such as pyrite, Ne isotopes can be used Come the source of spike BIFhosted gold deposit.

Claims

1. a kind of Ne gas isotope measure method, it is characterised in that methods described is to measure multiple calibration samples using mass spectrograph Obtain⁴⁰Ar⁺⁺With⁴⁰Ar⁺Relational expression, then measure testing sample⁴⁰Ar⁺, removed by calculating in testing sample⁴⁰Ar⁺⁺In quality To testing sample at number 20²⁰Ne influence, realizes that testing sample Ne gas isotopes are accurately measured；The mass spectrograph is described in measurement Measurement parameter when multiple calibration samples are with the testing sample is identical；The multiple calibration sample is free of Ne elements；It is each described The Ar contents of multiple calibration samples are different.

2. a kind of Ne gas isotope measure method as claimed in claim 1, it is characterised in that methods described specifically includes following step Suddenly：

（1）Multiple calibration samples are measured using mass spectrograph⁴⁰Ar⁺With⁴⁰Ar⁺⁺Obtained according to measurement result fitting⁴⁰Ar⁺⁺With⁴⁰Ar⁺ Relational expression；

（2）With the He of mass spectrograph measurement testing sample mass number 20⁴⁰Ar⁺Obtain the mass 20 and testing sample of testing sample⁴⁰Ar⁺Value；

（3）According to described⁴⁰Ar⁺⁺With⁴⁰Ar⁺Relational expression and the testing sample⁴⁰Ar⁺Value calculate obtain testing sample⁴⁰Ar⁺⁺；

（4）Testing sample²⁰Testing sample described in the mass 20- of Ne value=testing sample⁴⁰Ar⁺⁺。

3. a kind of Ne gas isotope measure method as claimed in claim 1, it is characterised in that the mass spectrograph measures testing sample When, the mass spectrograph is connected what is do not removed with adsorption and purification system with the activated carbon cold-trap and 70-90K cold pump under liquid nitrogen temperature Ar。

4. a kind of Ne gas isotope measure method as described in claim 1-3 is any, it is characterised in that the multiple calibration sample Ar semaphore scope be 300cps to 100000cps.

5. a kind of Ne gas isotope measure method as described in claim 1-3 is any, it is characterised in that the multiple calibration sample Number be more than 5.

6. a kind of Ne gas isotope measure method as described in claim 1-3 is any, it is characterised in that the measurement parameter refers to matter Compose parameter when ion gun and receiver measurement.

7. a kind of Ne gas isotope measure method as described in claim 1-3 is any, it is characterised in that the testing sample²⁰Ne semaphores are less than about 7 × 10 less than 50000cps, i.e. content^-11ccSTP。

8. a kind of Ne gas isotope measure method as described in claim 1-3 is any, it is characterised in that the testing sample²⁰Ne semaphores are less than 7 × 10 less than 5000cps, i.e. content^-12ccSTP。