The IonCCD detector was able to detect thermal ions and perform ion swarm imaging in a drift tube ion mobility spectrometer (DT-IMS) for the first time. High spatial resolution images of ion swarms were obtained in real-time, allowing characterization of ion diffusion and motion under electric fields. Dynamic imaging experiments with varying IMS parameters demonstrated the IonCCD's ability to provide high density imaging of ion swarms with 20 μm x 100 ms resolution. These results establish the IonCCD as a powerful new detector for ion mobility spectrometry.

1. First detection of thermal ions and ion swarm imaging in a
DT-IMS by means of a high spatial-resolution IonCCD™
Omar Hadjar1, Stephen Davila2, Gary Eiceman2
1OI Analytical, CMS field product, Mass Spectrometry and Ion Imaging, Pelham, AL
2 NMSU, Department of Chemistry and Biochemistry, Las Cruces, NM

2. Motivations
• To explore the capabilities of the IonCCD as a detector for IMS
• To extend detectability from keV down to thermal ions
• To provide real time, high density imaging of the ion swarm at
ambient pressures.
• To determine the diffusion of ion swarms in the drift region
• To characterize optics for ions
• To obtain sufficient experimental data on ion motion under electric
fields and form theoretical modeling and calculations

3. Introduction to the
IonCCD

4. Ring 1 Setup Schematics
Ring 2 of the DT-IMS
Ring 3
Ring 4
Ring 5
Ring 6
Ring 7
Ring 8
Ring 9
9
IonCCD Housing
Potential 8
1 2 3 4 5 6 7 8 9
7
Slit-Plate
6
Detector board
5
Cold foot
Slit-plate Chip
4 Femto-Amp
IonCCD housing
3
IonCCD chip 2
1
Distance

5. Experimental
Setup
Ring stack of the DT-IMS
IonCCD in SS enclosure
Camera box
IonCCD base lined signal
Picture shot while Stephen was changing the DT-IMS rings arrangement with
the IonCCD ON and recording no ion signal but an unperturbed base line

6. IonCCD housing voltage bias effect
1000 450
3 kV DT-IMS IonCCD
encosure
3 kV
bias:
800 70V 2 kV
50V 400
30V
IonCCD signal (dN)
25V
600 20V
14V 350
10V
6V
400
4V
1.6V
300
IonCCD integrated signal (kdN)
0.8V
200 0.2V
0.1V
0V
250
0
-10 -5 0 5 10 15 20
500 IonCCD
2 kV DT-IMS 200
encosure
bias:
70V
400 50V
30V 150
IonCCD signal (dN)
25V
20V
300
14V
10V 100
6V
200 4V
1.6V
0.8V
0.2V 50
100
0V
0 0
-10 -5 0 5 10 15 20 0 20 40 60 80
IonCCD X axis (mm) IonCCD enclosure Bias (V)
6 rings DT-IMS (pre-ring lens & slit disc)

7. Detection Efficiency
800 400 80
IMS voltage (V)
3000
700 2500
2000
1500
1000 300 60
600
500
IonCCD integrated signal (kdN)
FemtoAmplifier (pA)
500
IonCCD signal (dN)
200 40
400
300
100 20
200
100
0 0
0
-25 -20 -15 -10 -5 0 5 10 15 20 25 0 500 1000 1500 2000 2500 3000
IonCCD coordinates (mm) IMS voltage (V)

8. IonCCD vs. FemtoAmp response to the IMS ion throughput
350
Equation y = a + b*
Adj. R-Squar 0.99793
300 Value Standard Erro
E Intercept -22913.3526 5498.23184
E Slope 5263.6508 119.6966
250
IonCCD (kdN)
200
150
100
50
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70
FemtoAmplifier (pA)
The integrated profiles are plotted here
against the Femto-Amplifier response when
operated at 1011 gain. This comparative study
was conducted at same experimental
condition with a 16x1mm2 slit plate and
grounded IonCCD plate to expose both
detection surfaces to the same ion beam cross
section hence the same total ion current.

9. 10000
IonCCD detection efficiency at
different IMS high voltage bias
IonCCD responce (ion/dN)
noise floor (12 dN)
1000
We observed a slight decrease of the IonCCD detection
efficiency at lower IMS HV. This can be due to experiment-
100 to-experiment variation, or witnessing the effect of the
floating pixels, during charge integration time, on the ion
collection (retarding field effect).
10
10000
1
1000 1500 2000 2500 3000
IMS voltage (V)
IonCCD response (ion/dN)
1000 5
Broad band detection>10
Using the averaged value obtained we show
clearly that not only the IonCCD not detects 100
thermal ions but equally important maintain its
detection efficiency from ~keV down to ~meV ion
energies. By analogy to optical CCDs, the IonCCD
10
has a broad band detection > 105
Ion energy range of maintained
1
IonCCD detection efficiency 0.01 0.1 1 10 100 1000 10000
Ion energy (eV)

10. B&N gate Imaging
16 mm B&N Gate
1000
nd
2 ring
transversal
800
IonCCD signal (dN) Offset Y values
600 740V
720V
700V
680V
400 660V
650V
640V
630V
200
664V
0
-10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18
IonCCD coordinates (mm)

11. 16 mm B&N Gate
th
6 ring
800 transversal
IonCCD signal (dN) Offset Y values
600
2070V
2050V
400 2030V
2010V
2000V
1990V
200
1980V
1970V
1989V
0
-10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18
IonCCD coordinates (mm)

12. 3.5
B&N Gate Gate location 8th ring
800 8th ring +5V 3.0 6th ring
Structure FWHM (mm)
6th ring -9V 2nd ring
2nd ring -24V 2.5
700
2.0
truncated
1.5
IonCCD signal (dN) Offset Y values
600
1.0
0.5
500
0.0
-8 -6 -4 -2 0 2 4 6 8
400
Structure centroid location (mm)
4.0
y = Intercept + B1*x^1
Equation
average peak width (mm)
3.5 Weight Instrumental
300 Residual 0.02831
Sum of
Squares
3.0 Adj. R-Squar 0.99857
Value Standard
Error
200
2.5 C
Intercept 0.9567 0.02184
B1 0.1940 0.00518
2.0
100
1.5
ring-to-ring=10 mm
0 1.0
-25 -20 -15 -10 -5 0 5 10 15 20 25 0 1 2 3 4 5 6 7 8 9
IonCCD coordinates (mm) Gate position(ring #)

13. The slope suggests that diffusion in those conditions
(3000V/8 rings=80mm, and Please check the total distance)
result in ~0.2 mm radial expansion for every 10mm axial
motion (~2%)
3000V/80mm
0.194 mm
10 mm
300 ml/min

14. Opening and closing settings of the B&N gate
B&N gate
100000
IonCCD integrated singnal (dN)
10000
1000 B&N 2nd transversal
B&N 6th transversal
100
-100 -50 0 50 100
wire-set V (V)

15. Tyndall gate Imaging
16 mm Tyndall Gate
nd
2 ring
600 collinear
IonCCD signal (dN) Offset Y values
740V front
400 720V front
700V front
660V front
664V back
200
0
-10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18
IonCCD coordinates (mm)

16. Front set scan Back set scan
1400 1000
Tyndall Gate 16 mm
16 mm Tyndall Gate
nd nd
2 ring 2 ring
1200 transversal transversal
800
IonCCD signal (dN) Offset Y values
IonCCD signal (dN) Offset Y values
1000
600
800
720V back
740V front 700V back
600 720V front 690V back
700V front 400 680V back
680V front 660V back
400 670V front 640V back
660V front 620V back
200
664V back 664V front
200
0 0
-10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18
IonCCD coordinates (mm) IonCCD coordinates (mm)

17. 16 mm Tyndall Gate
th
500 6 ring
collinear
IonCCD signal (dN) Offset Y values
400
2070V front
2060V front
300 2040V front
2020V front
2010V front
2000V front
200
1989V front
1989V back
100
0
-10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18
IonCCD coordinates (mm)

18. Front set scan Back set scan
800
1000 Tyndall Gate 16 mm Tyndall Gate
16 mm 6th ring 6th ring
transversal transversal
800
600
IonCCD signal (dN) Offset Y values
IonCCD signal (dN) Offset Y values
600
400
2120V front 2060V back
2100V front 2040V back
400
2080V front 2020V back
2060V front 2000V back
2040V front 1980 back
200 1960V back
2020V front
200
2000V front 1989V front
1980V front
1989V back
0 0
-10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18
IonCCD coordinates (mm) IonCCD coordinates (mm)

19. • 1117 V, 2 ring
Dynamic Images with IMS • Ion source in-and-out
• 10 pixels avg., 10 frames avg.
Parameters • 95 MB file
IonCCD signal (dN)

20. • Zoom window, 35 sec, 19 mm
Dynamic Images with IMS • No pixel and frame avg.
• 24 µm x 100 ms Resolution
Parameters
IonCCD signal (dN)

21. Increasing vs. decreasing E-field effects
4000
3000
Ring potential (V)
2000
1000
Increasing
0 Decreasing
0 2 4 6 8 10
ring # source-to-IonCCD
1000 Increasing E-field
Decreasing E-field
IonCCD signal (dN)
800
345 kdN
600
400
200 170 kdN
0
-10 -5 0 5 10
IonCCD X axis (mm)

22. Conclusions
• IonCCD showed linear response and detection of ions in the thermal
energy regime, extending the detection band with from thermal to
medium energy regime (10 meV – 10 keV)
• The first high resolution imaging of ion diffusion determined
experimentally with better than 0.1 mm resolution in one direction.
• Shadowing of the ions observed from shutter wires throughout the
drift region of the IMS.
• Gathered experimental data for improved ion modeling.
Acknowledgements
OI Analytical, for funding the collaborative work

23. Questions
I