Transcript Denton

COMPOSITION ? (QUALITATIVE ANALYSIS)
HOW MUCH ? (QUANTITATIVE ANALYSIS)
WHAT FORM ? (SPECIATION)
Topic I
Mass Spectrometry
Present Detector Technology – Faraday Cups
Collector Electrode
Faraday Cage
Out to amplifier
Load Resistor
Out to amplifier
•Gain is stable and precisely
known (gain=1)
•Bandwidth is consistent with
use in sector-based mass
spectrometry
•Useful for Iion  10-15 amp
(1 ion/sec  1.6  10-19 amps)
•Implies that one needs about
6250 ions/sec for detection by
Faraday cup
High Z
“FARADAY
ELECTRODE”
output
Electron Multiplier Detector
Incident Ion
Secondary Electrons
Electron Multiplier Detector
Detection Efficiency
Electron multiplier has
a gain that is
dependent upon the
mass or kinetic energy
of the incoming ion.
0
Mass (m/z)
Electron Multiplier Detector
Detection Efficiency (%)
100
80
60
40
20
0
10
102
103
Energy (eV)
104
Focal Plane Array
hn
e
-
PtSi Photoactive Layer
In bump
bonds
Silicon Multiplexer
Individual preamps
for each pixel
RESET
36 fF
“FARADAY
CUP”
MUX
4.4 V / e- 20 e-- read noise @ 77 K
Mattauch-Herzog Mass
Spectrometer Geometry
Ion Source
-
Magnetic Sector
+
Electrostatic Sector
Array Detector on
Focal Plane
Design Specifications
•
•
•
•
•
Noise - 5 electrons read noise (highest gain)
39.6 microvolts / electron (highest gain)
Well size - 80,000 e to 16,000,000 e
50 micron pitch
Read rate - 1 mega sample per second into
30pfd &10kohm
• Nondestructive / Destructive Readout
RESET
Gain
990
10 f
f F
F
“FARADAY
ELECTRODE”
MUX
Detection Limit
2.5 electrons of read noise
with NDRO
8 IONS !
& we are still optimizing it !!
Keep tuned
35 lbs.
75 watts
GC, Pumps
Mass spec.
etc.
CMS
Ion Mobility Spectrometry
Applications Using Ion Mobility Spectrometers
Field-Portable detection of
chemical warfare agents
Detection of explosives, nerve
agents, toxins, and other
hazardous chemicals at safety
inspection stations and in the
environment
Ion Mobility Spectrometer
IMS is a technique that is being
employed to solve problems where
portable instrumentation and
ruggedness is necessary
 New Instruments Demand Lower
Detection Limits
 Must Operate through a Wide Range
of Temperatures
 Must Operate at Atmospheric
Pressure
Structural
conformation studies of
proteins, polymers, and
various other molecules
 High S/N Ratio
Ion Mobility Spectrometer
Electric Field
Ionization
Chamber
Drift Region
bFaraday
Plate
Ion Shutter
Drift Gas Inlet
Gas Inlet
Gas Outlet
Drift Rings
Chemical Identification Based Upon Ion Mobility
Relationship of Ion Mobility to Molecular Terms
Mobility: K =
Drift Velocity: vd = K E
3 e
K=
16 N
E
td
m
N
T
W
 
1 1
+
m M
Electric Field Strength
Drift Time
Ion Mass (analyte)
Number Density
Temperature
Collision Integral
d
e
M
k
r
D
d
td E
2 p 1+D
k T p r2 W
Drift Path Length
Unit Charge
Molecular Mass (drift gas)
Boltzmann-Constant
Minimum in Potential Curve
Correction Term
High Z
“FARADAY
ELECTRODE”
output
RESET
8 fF
“FARADAY
ELECTRODE”
MUX
New interlocking 8 ring microIMS
1-31-05
25pg TNT -1825VDC Emco PS, 90C 100/50 ml/min Cl-/Air
Filament, inj 125C. Filters OFF
Resolution 84. Run a baseline noise 0.005 S/N=30
Detection Limit = 2.5 pg
5pg TNT 95 oC 25V Injector Block 0.85A
Filament, 1200 us Pulse B.C. FIRW on ( 0.9 pg Det. Lmt.)
8in.
12 in.
18 in.
Proposed Vehicle Based IMS
1700
Intensity (ADU)
1600
1500
1400
47 attograms in
single sweep
RDX
1300
e- peak
Detection Limit = 5 attograms RDX
1200
0
20
40
60
Time (ms)
80
100
120
Conclusions
• CTIA is ideal for IMS
– Fast (1 MHz or higher per pixel)
– Low read noise
– 1000 x sensitivity improvement over current
micro-IMS device.
– Expect further improvement with differential
devices and cooling.
– Don’t need low secondary electron yield
coatings or exotic geometries for IMS.
Conclusions
• CTIA is ideal for IMS
– Fast (1 MHz or higher per pixel)
– Low read noise
– 1000 x 10,000 x sensitivity improvement over
current micro-IMS device.
– Expect further improvement with differential
devices and cooling.
– Don’t need low secondary electron yield
coatings or exotic geometries for IMS.
Miniature Optical Bench
14mm
How do you make an optical
bench that is just 14mm long?
Axsun’s Handheld Substance ID
Solutions
Raman Handheld Substance Identifier Concept
Fiber Optics
Raman Probe
TEC High Power
Laser Diode
TEC
Spectrometer
Battery
Raman Spectral Range
Dependence on Excitation l
224.3nm
246nm
244.0nm
256.5nm
270.4nm
488.0nm
540.8nm
606.4nm
785.0nm
931.2nm
1144.3nm
980nm
1225nm
1450nm
Excitation l
0
2000
Raman Shift (cm-1)
4000
NIR Spectroscopy/Imaging With Focal Plane Arrays
•900-1700 nm is critical “molecular fingerprint” region for scientific research and analysis of
food, pharmaceutical, chemical, and plastic products.
•Ideal NIR sensor will have high QE between 900-1700 nm, high sensitivity, high dynamic
range.
Photon-Processor™
Extreme Low Light Level Digital Video
Imager
Photoelectrons
CMOS Imager
Light
Photocathode
Video
Output
Photon-Processor™
• Low Cost

Day/Night Operation
• Patented Technology

SXGA (1024 X 1280) Resolution

Low Power <600 Mw @ 3 VDC
• Camera Electronics On-chip
Photoelectrons
CMOS Imager
Light
Photocathode
Video Output
Complete NIR Spectrometer
Spectrometer
PC and
software
Sample
Wired or
wireless
Butterfly packages
Wavelength
Reference
DSP
processor
SLED
source
MEMS
tunable
filter
Power
Reference
24-bit A/D
converters
Amp
Blue lines are light, red are
electrical
Single
element
InGaAs
detector
Probe or optics
Reference Block Diagram
• WARM (Wavelength & Amplitude Reference Module)
– Ultra stable beamsplitters tap off known quantities of light
– Absolute wavelength reference provided by an integrated quartz
etalon and a miniature acetylene gas cell that are temperature
controlled to 0.1oC
– Amplitude reference provided by matched single element
photodetectors that divide out responses from every point of a scan
WARM (wave, amplitude- reference) Module
• Tunable laser
spectrometer, in
portable package
• With embedded PC and
sample interface
Sample
interface
LCD
Display
Tunable laser
spectrometer