measurements of Sr and Nd at the nanogram level using the Phoenix - PowerPoint PPT Presentation

High precision isotope ratio measurements of Sr and Nd at the nanogram level using the Phoenix TIMS with next generation Faraday detectors Zenon Palacz Isotopx Limited 34th IGC presentation 2958

34th IGC presentation 2958

What are the parameters required for high precision measurements of small samples? (on Faraday collectors) • High Sensitivity – Instrument sensitivity – Use of activators • Low noise – Close to theoretical Johnson noise – Baseline stability • Gain stability between detectors – Required for static analyses • Multidynamic measurements – Eliminates gain and efficiencies – But can it be used on small samples? 34th IGC presentation 2958

How quiet are X act amplifier/resistor boards 50 45 Faraday Noise each point average of 9 channels 40 Measured 35 30 m V 25 20 15 10 5 Theoretical 0 0 10 20 30 40 50 60 70 80 90 100 Integration time SECONDS 34th IGC presentation 2958

How quiet are X act amplifier/resistor boards 50 45 Faraday Noise each point average of 9 channels 40 35 Measured 30 m V 25 20 15 Theoretical 10 5 0 0 5 10 15 20 Integration time SECONDS 34th IGC presentation 2958

Noise comparison between 1e 11 and 1T resistors Noise (Amps) Integration time 1e 12 ohm 1e 11 ohm 1e 11 /1e 12 (seconds) n=5 n=4 Noise comparison between 1T and 1e11 ohm resistors 3.0E-16 1 2.3E-16 3.8E-16 1.7 2.6E-16 2.2E-16 Noise (amps) 5 1.0E-16 1.7E-16 1.6 1.8E-16 1T 1e11 ohm 1.4E-16 10 6.5E-17 1.2E-16 1.8 1.0E-16 6.0E-17 20 5.1E-17 7.3E-17 1.4 2.0E-17 0 50 100 150 200 250 300 350 40 3.6E-17 6.3E-17 1.7 Integration time (seconds) 60 3.6E-17 5.1E-17 1.4 300 3.5E-17 4.9E-17 1.4 34th IGC presentation 2958

How fast are X act resistors (1e 11 ohm)? 20.00 15.00 Old Baseline in <1 second PPM of intensity specification 10.00 5.00 0.00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 -5.00 -10.00 Seconds 34th IGC presentation 2958

1T baseline in 4 seconds 1T signal response 20 5ppm of signal in 3 15 PPM of signal seconds 10 5 0 -5 -10 0.0 2.0 4.0 6.0 8.0 10.0 12.0 Seconds 34th IGC presentation 2958

Gain stability 5ppm over 1 month No drift. CCGains H2 relative to Axial over 1 month 0.99775 Gain relative to axial collector 0.99774 0.99773 0.99772 0.997732+/-0.000005 y = 6E-08x + 0.9977 5ppm 1RSD 0.99771 0 10 20 30 40 50 60 70 80 Measurement 34th IGC presentation 2958

Day averages Reduced scatter shows subtle coherent trends. Measured on factory floor with no environmental temperature control Gain Day averages 15 Series1 10 Series2 Gain Drift (PPM) Series3 5 Series4 0 Series5 Series6 -5 Series7 -10 Series8 -15 - 5 10 15 20 25 30 Days 34th IGC presentation 2958

Sr dynamic precision 3ppm reproducibility (5volt ion beam) 200ng NBS987 Dynamic 0.710260 0.7102444+/-0.0000021, 3ppm 1RSD 0.710255 1RSD 87 Sr/ 86 Sr 0.710250 0.710245 0.710240 0.710235 200ng NBS 987 0.710230 0 2 4 6 8 10 12 14 16 18 20 22 Filament 34th IGC presentation 2958

Static precision 5ppm no gain corrections between analyses (5 volt ion beam) 200ng NBS 987 STATIC 0.710280 0.710275 0.710270 87 Sr/ 86 Sr 0.710265 0.710260 0.710255 0.710250 0.710245 0.7102577+/- 0.0000035, 5ppm 0.710240 1RSD 0 5 10 15 20 25 Filament 34th IGC presentation 2958

How small a sample of Nd can be measured on Faradays • Nd+ ion atom efficiency is about 2.5% (triple filament) • NdO+ is higher than this. 34th IGC presentation 2958

How small an ion beam can we measure with good precision and accuracy? 50mv on 1e 11 , 10mv on 1T 142 Nd 142 Nd 143 Nd/ 144 Nd 145 Nd/ 144 Nd 142 Nd/ 144 Nd (amps) (mv) %1se %1se %1se 7.1E-12 706 0.512095 0.0003 0.348402 0.0003 1.141827 0.0005 4.9E-12 485 0.512096 0.0004 0.348395 0.0004 1.141819 0.0006 3.0E-12 296 0.512082 0.0008 0.348399 0.0008 1.141837 0.0012 1E+11 1.1E-12 105 0.512113 0.0016 0.348371 0.0020 1.141793 0.0019 4.9E-13 49 0.512057 0.0028 0.348383 0.0030 1.141822 0.0042 1.1E-13 11 0.512261 0.0106 0.348341 0.0135 1.143178 0.0139 4.9E-14 5 0.511754 0.0191 0.348499 0.0340 1.142667 0.0265 3.6E-14 4 0.512215 0.0257 0.348698 0.0274 1.142779 0.0221 142 Nd 142 Nd 143 Nd/ 144 Nd 145 Nd/ 144 Nd 142 Nd/ 144 Nd (amps) (mv) %1se %1se %1se 6.88E-12 688 0.512121 0.0003 0.348419 0.0003 1.141855 0.0005 4.98E-12 498 0.512127 0.0003 0.348421 0.0003 1.141861 0.0005 2.94E-12 294 0.512117 0.0006 0.348415 0.0006 1.141837 0.0007 1T 9.67E-13 97 0.512169 0.0010 0.348432 0.0017 1.141870 0.0013 5.16E-13 52 0.512116 0.0023 0.348425 0.0022 1.141833 0.0018 1.26E-13 13 0.512106 0.0042 0.348400 0.0050 1.141863 0.0045 4.83E-14 5 0.512418 0.0083 0.348734 0.0123 1.141554 0.0105 34th IGC presentation 2958

Errors expand below 1e -13 A 0.51280 0.51260 143 Nd/ 144 Nd 0.51240 0.51220 1.00E+11 0.51200 1T 0.51180 0.51160 0.51140 1.0E-14 1.0E-13 1.0E-12 1.0E-11 142 Nd intensity (amps) 34th IGC presentation 2958

10.5% ion/atom efficiency <20ppm reproducibility 300mv 142 Nd 16 O 2ng NdO 1T resistor data 142 Nd 16 O ion/atom 142 Nd/ 144 Nd 143 Nd/ 144 Nd 145 Nd/ 144 Nd 148 Nd/ 144 Nd amps efficiency %1se %1se %1se %1se Minutes 1 1.141818 0.0008 0.512085 0.0006 0.348413 0.0006 0.241589 0.0012 3.3E-12 152 9.0% 2 1.141821 0.0008 0.512099 0.0008 0.348420 0.0009 0.241589 0.0015 2.9E-12 187 9.5% 3 1.141816 0.0007 0.512103 0.0007 0.348419 0.0007 0.241594 0.0010 3.1E-12 206 11.4% 4 1.141764 0.0010 0.512085 0.0007 0.348409 0.0006 0.241603 0.0013 3.1E-12 207 11.5% 5 1.141838 0.0010 0.512080 0.0007 0.348406 0.0006 0.241590 0.0015 3.1E-12 229 12.6% 6 1.141776 0.0010 0.512093 0.0007 0.348428 0.0006 0.241598 0.0015 3.1E-12 206 11.5% 7 1.141789 0.0009 0.512091 0.0007 0.348423 0.0006 0.241597 0.0014 3.2E-12 206 11.5% 8 1.141773 0.0011 0.512078 0.0007 0.348412 0.0007 0.241607 0.0016 3.1E-12 187 10.1% 9 1.141818 0.0009 0.512097 0.0007 0.348419 0.0006 0.241593 0.0013 3.2E-12 206 11.6% 10 1.141762 0.0014 0.512084 0.0009 0.348417 0.0008 0.241587 0.0014 3.2E-12 103 5.8% 11 1.141838 0.0007 0.512109 0.0006 0.348410 0.0006 0.241598 0.0011 3.0E-12 204 11.0% Mean 1.141801 0.0009 0.512091 0.0007 0.348416 0.0007 0.241595 0.0013 3.1E-12 190 10.5% 1SD 0.000029 0.0002 0.000010 0.0001 0.000006 0.0001 0.000006 0.0002 1.1E-13 35 2% 1RSD 0.0025% 0.0019% 0.0018% 0.0026% 34th IGC presentation 2958

2ng Nd measured as oxide at 300mv 142 Nd 16 O 2ng NdO 0.51212 Isotopx preferred value 0.51211 0.512104 143 Nd/ 144 Nd 0.51210 0.512091+/-0.000010 (19ppm 1RSD) 0.51209 1T 1e11 ohm 0.51208 0.51207 0.512076+/-0.000007 0.51206 (14ppm 1RSD) 0.51205 0 5 10 15 20 25 Sample 34th IGC presentation 2958

Total evaporation measurements • Widely used in nuclear applications to overcome mass fractionation by taking the average isotopic composition of the whole evaporation process. • Baselines , peak centring and focussing at the start of the measurement prior to filament current ramping • All above must remain stable during the evaporation. • Used for small Sr in this application • Potential benefit for micro-drilled samples, ice cores? 34th IGC presentation 2958

Total Evaporation (summed isotope ratios) 88 Sr Ionization End of analysis profile INTENSITY 86 Sr 87 Sr Baseline TIME Baselines must remain constant throughout analysis 34th IGC presentation 2958

50ng Sr ion beam profile 7v for nearly 2 hours Efficiency 3.5% (No focussing or peak centring) 50ng NBS987 8.0E-11 7.0E-11 6.0E-11 88Sr (amps) 5.0E-11 4.0E-11 3.0E-11 2.0E-11 1.0E-11 0.0E+00 0 1000 2000 3000 4000 5000 SECONDS 34th IGC presentation 2958

86 Sr/ 88 Sr (summed) 50ng NBS 987 86/88 summed 1.2040E-01 1.2020E-01 1.2000E-01 1.1980E-01 1.1960E-01 1.1940E-01 1.1920E-01 1.1900E-01 1.1880E-01 0 1000 2000 3000 4000 5000 34th IGC presentation 2958

87 Sr/ 86 Sr (summed) 87/86N SUMMED 7.1026E-01 7.1025E-01 7.1024E-01 7.1023E-01 0.710243 7.1022E-01 7.1021E-01 7.1020E-01 7.1019E-01 7.1018E-01 7.1017E-01 7.1016E-01 0 1000 2000 3000 4000 5000 34th IGC presentation 2958

1ng Sr 3volts 88 Sr for 150 minutes Efficiency= 13% Sr88 S1 int 8.00E-11 7.00E-11 Intensity (amps) 6.00E-11 5.00E-11 4.00E-11 3.00E-11 2.00E-11 1.00E-11 0.00E+00 0 1 000 2000 3000 4000 5000 6000 7000 8000 9000 Seconds 34th IGC presentation 2958

Total evaporation measurements of NBS 987 <1ng Total Evaporation NBS 987 100pg 200pg 500pg 1ng 0.710244 0.710320 0.710249 0.710266 0.710255 0.710279 0.710263 0.710262 0.710285 0.710269 0.710265 0.710274 0.710242 0.710222 0.710264 0.710278 0.710256 0.710298 0.710273 0.710253 0.710320 0.710229 0.710253 0.710265 0.710299 0.710250 0.710249 0.710257 0.710229 0.710249 0.710273 0.710285 0.710272 0.710254 0.710303 0.710268 0.710258 mean 0.710272 0.710267 0.710261 0.710264 1SD 0.000031 0.000036 0.000010 0.000009 1RSD (PPM) 43 50 14 12 34th IGC presentation 2958

Ion/Atom detection efficiency for Sr with TaCl activator on rhenium filament 35% Max transmission due to 30% Ion/atom efficiency z focussing 25% 20% ? 15% 10% 5% 0% 0 1 10 100 Sr (ng) 34th IGC presentation 2958