SPECIFICATION
Requirements for a 193nm laser ablation system at NIGL at the British
Geological Survey, Keyworth, Nottingham.
Guiding Philosophy
The scientific activities of the NERC Isotope Geosciences Laboratory encompass a wide range of isotope measurements and applications. A large proportion of these activities in the PIMS-Tracer and Geochronology Facilities utilize our current laser ablation system and have placed NIGL as one of the foremost laboratories in the world for laser ablation isotope research.
The new laser will be coupled to an ICP mass spectrometer in conjunction with a desolvating nebuliser and excellent performance is required with these devices in all modes of operation. Our primary purpose for the new laser is to further develop our U-Pb geochronology, Hf and Sr isotope capabilities and develop new and novel applications in isotope science. Due to the level of demand for the service NIGL provides, it is anticipated that the new laser system will be used almost continuously throughout its lifetime.
General Requirements
Tenderers are asked to include the following details as part of their tender: a) a detailed breakdown of costings for all items included in the specification; b) details of any third party components included within the specifications which the Council could purchase directly from manufactures (e.g. computer system and peripherals, switching valves, etc); c) details of warranty provisions; d) details and costings of spares kit; e) details of maintenance arrangements/agreements; f) details of service engineer’s call out charges (per day).
Tenderers are asked to submit a tender for a complete laser ablation system only (i.e. including laser, beam delivery optics, viewing optics, sample cell and appropriate software control). If normally manufacturing only part of the system please also state the nature of any third party relationships.
We outline here key specifications that NIGL deems to be prerequisites to achieving our scientific objectives.
The laser system must exhibit:
1) 193nm wavelength laser beam (derived from solid state or gas state)
2) Spot sizes from <5um to 400um with a cylindrical, flat-bottomed profile across the entire spot size range up to depth:diameter ratios of 6:1

a. <5um must be achieved whilst ablating a colourless zircon crystal and reproducing a flat bottomed, cylindrical ablation crater to 30um depth at a constant beam energy b. a 30 x 30 x 5um (WxLxD) flat bottomed, cylindrical ablation crater must be achieved whilst ablating a colourless zircon crystal at repetition rates from 1-20Hz across a range of beam energies
3) Short pulse duration - preferably <5ns (nanosecond rather than femtosecond is preferred)
4) Consistent power density for selected power output across spot size range
5) Homogeneous beam profile across power and spot size range
6) Variable repetition rates from 1-20Hz
7) Computer-controlled motorised x-y-z translation stage reproducible to
+/- 0.5 m after travelling the total axis distance and back.
8) Simple and robust sample changing mechanism to allow diversion of gas flows and change of sample without extinguishing ICP. a. If a valve switching mechanism is used for this purpose, the design should be optimized such that particulate materials cannot be trapped or collected within the valve system, leading to leakage and cross-contamination. Detailed drawings of the valves and/or a dismantled valve should be provided for reference.
9) mass flow controllers calibrated for Ar, N & He
10) a lifetime for the laser generating medium and beam delivery optics of
>1 month (c.6 million shots, gas-state) or >1 year (c.100 million shots, solid state), assuming 10Hz, 10hrs/day, 22 working days/month. The lifetime of all critical components within the system should be specified.
11) Compatible with all models of single and multiple collector and quadrupole ICP-MS instruments
12) a firing link to the mass spectrometer software to allow automated analysis
13) an integral energy meter which can be easily checked and recalibrated using an external energy meter
14) high quality viewing optics displaying minimal distortion of any kind at all magnifications.
15) Power a. Output b. Density
- >1mJ at 193nm
- >7J.cm
-2 at the sample surface
Please provide details of all final beam delivery characteristics (e.g. divergence, beam profile, homogeneity, energy distribution, etc.).
16) Variable light source

a. polarized transmitted, reflected/coaxial and ring/flood illumination with the ability to vary each individually and use in combination as required
17) Cell design a. the ablation cell will ideally be constructed from an inert nondeforming material such as PEEK or similar material b. Multiple application-specific designs should ideally be available including a large volume general purpose cell and one specific to the application of LA U-Pb geochronology using both 1 inch
(2.54cm) resin grain mounts and petrographic thin sections.
Ideally the system will be compatible with or adaptable to receive the current NIGL lowvolume ‘zircon cell’ c. Technical drawings of the ablation cell(s) supplied and relevant system housing are requested to be included d. Transmitted and reflected light options should be usable with both grain mount and thin section sample media as well as any general purpose ring/flood illumination.
H&S
18) Full enclosure of laser system conforming to Class 1 status with all relevant safety interlocks
– the laser system must comply with all appropriate EU regulations
19) Complete isolation of electrical systems with relevant safety interlocks
20) Early warning of required attention to essential systems e.g. cooling system, etc.
21) Complete isolation and early warning system in case of failure of the gas handling facilities for an excimer laser
22) Information on how the gas systems of an excimer laser are handled safely and any special arrangements (and estimated costs) that will be required to be fitted into the laboratory.
Performance specifications – using a range of and/or specified ablation conditions
23) Particle size range should be proven – all particles should be <200nm when ablating NIST 610-614, with 90% by volume <100nm for NIST
614.
24) Homogeneous beam profile (flat-topped) should be proven across whole range of energies and spot size settings
25) Shot-to-shot stability should be demonstrated with regard to energy, pulse duration and beam profile at 20, 10, 4, & 2 Hz
26) Change of ablation pit profile with depth should be demonstrated up to depth/diameter ratios of 10.
27) Long-term energy stability – <2% (1SD) over 8 hours
28) The working distance of the optics should be stated
29) The position of the point of laser focus relative to the sample surface when the viewing optics are focused on the sample surface and the

depth of field, i.e. the size of the zone of focus, of the optics should be stated. This information must be provided.
Target analytical performance
(these will form part of the assessment tests; these are the analyticals targets expected to be achieved if the above technical specifications are demonstrated)
30) 206 Pb/ 238 U stability - <0.1% 1SE, <<1% 2SD when ablating a crater in zircon 91500 with depth:diameter ~1:1
31) Epsilon Hf reproducibility ( 176 Hf/ 177 Hf) <<1 (2SD) using a 50um ablation crater (depth/diameter ratio <1) when ablating Mud Tank or Plesovice reference zircons
32) Fractionation index – 1 +/- 10% on NIST 614 for all masses from 7 Li to
238 U (F.I. = (X’’/Y)/(X’/Y) where X’ = signal of element X for first 30secs ablation; X’’ = signal of element X for second 30secs ablation; Y = normalizing element signal).
33) Measured 238 U/ 232 Th on NIST 612 – ~1 after appropriate tune up of mass spectrometer
Supplied PC specification
34) The supplied PC should have:
~3GHz microprocessor
~300Gb hard disk space
2Gb RAM memory
2 high quality, high resolution flat-screen colour monitors
Multiple (3+) USB2 ports
CD/DVD reader/writer
all necessary manufacturers and essential third party hardware and software required for communication with the laser system
an appropriate network card for file transfer
an appropriate graphics card for output of high quality image
Software features
35) Ability to capture video clips, download images, create and save maps of sample mounts and receive x-y-z co-ordinates for navigation
36) Image file format allowing easy export to MSOffice, CorelDraw and/or
Adobe packages
37) Ability to implement and place at will (drag-and-drop, copy, move, rotate, resize, etc) variable ablation patterns (raster, line, spot, grid/line of spots, etc).
38) Programmable to accept firing and positioning instructions from mass spectrometer software
39) Extremely user friendly – total novice able to use ablation software after
30mins instruction

40) Include hard (CD or DVD) installation discs of all installed software
41) Free upgrades to ablation control software for the lifetime of the laser system.
Information/Services/Equipment to be provided with Laser system
42) Complete & comprehensive operating manual with schematics and electronics diagrams of laser system and ancillary components, e.g. power supply, switching valves, cell, etc.
43) Spares kit and list of parts with guide prices
44) Installation and training in operation and maintenance should be included in the tender package
45) Servicing - field replacement of component parts should be quick and easy. Response times from order should be fast and efficient with service engineers readily available.
46) Tenderers are asked to clearly state the lead time for receipt of goods as well as all consumable and running costs. Detail of expected life span and current cost should be given for all components and consumables expected to require replacement within 3yrs.