Specular Reflection

Specular reflection sampling represents a very important technique useful for the measurement of thin films on reflective substrates, the analysis of bulk materials and the measurement of mono-molecular layers on a substrate material. Often this technique provides a means of sample analysis with no sample preparation – keeping the sample intact for subsequent measurements.

VeeMAX III, Page 63 63 Thin Films and More substrate using the VeeMAX III. Optimization of the analysis of a multi-layered coating on metal AUTOMATED OPTION From monolayers thick films,to allrelatively experiments may be orientation and spectroelectrochemistry.polymer determination of monolayers and ultra-thin films, of analysis include depth profiling, samples. Typical VeeMAX a wide range of to analyze III applications optical design (U.S. Patent No. 5,106,196) makes it a key accessory specular reflectance accessory.grade Itsunique variable angle The PIKE Technologies VeeMAX III is a high-performance research- •  •  •  •  •  •  •  vapor and carbondioxide interferences Sealed andpurgeable opticaldesigntoeliminate water high-precision experiments Automated optionwithAutoPRO software for automated, reflectionOptional single –see ATR crystals ATR section orientation polymer monolayer andstudyof analysis positionfor IRpolarizer–essentialfor Integrated incidence of Optimize specularreflectance results withselectable angle thick films thinfilmsandmonolayers to Measurementrelatively of increments1 degree in incidence–from 30to80degrees Selectable of angle F s e r u t a e Specular ReflectanceAccessory VeeMAX III–TheUltimate Variable Angle

complete configuration options. angle ATR experiments. Please see the ATR section of our catalog for accessory may be fitted with an ATR flat plate allowing for variable ZnSe polarizer and MCT detector. specular reflectance accessory set at 80 degrees angle of incidence, FTIR spectrum of thiol monolayer measured using the VeeMAX III Proprietary beam path within the VeeMAX III specular reflectance accessory. changing polarizer orientation. breaking accessed while never the purge when setting dial is easily the spectrometer.either the source or detector side of The polarizer on into the accessory allowing the PIKE polarizer to be inserted decreases sampling time. It is furnished with two polarizer mounts the need to purge the entire This significantly sample compartment. the VeeMAX which eliminates III is its enclosed optics for purging, 3/8” apertures are provided. design feature Another important of aremirrors diamond turned for optimal performance. incidence. All powered throughput at is realized high angles of even the optics, excellent and the quality of this accessory design of area, large samples mayThanks to the optical be readily analyzed. Designed forsampling surface. unrestricted access to the sampling the accessory.front panel of Changing the angle is as easy as turning the angle selector on the incidence from 30 to 80 degrees. the angle of optimized by varying To further expand on the versatility of the VeeMAX III, the To sample geometries, masks with 2”, 5/8” and suit different To make measurements, down on the the sample is placed face

VeeMAX III – The Ultimate Variable Angle Specular Reflectance Accessory

An optional automated version of the VeeMAX III accessory is S p e c i f i c a t i o n s S available. It features a precision motor with USB interface and PIKE p Technologies AutoPRO software. Operation of the VeeMAX III can be Optics All reflective ecular integrated with the spectrometer software of most FTIR instruments, Angle of Incidence Range 30 to 80 degrees which allows the operator to precisely and reliably control a wide Sample Masks 2”, 5/8” and 3/8” range of angles of incidence and data collection simultaneously Purge Sealing Purge tubes and purge barb included from a computer keyboard. Automated sampling decreases operator error and increases workflow productivity. Other advantages of an Dimensions (W x D x H) 177 x 92 x 162 mm (excludes baseplate) Automated VeeMAX III accessory include FTIR Compatibility Most, specify model and type

Spectroelectrochemical R • Computer-controlled precision, accuracy and repeatability

Vessel Dimensions 25 mm dia tapering to 19 mm, 25 mm tall e

• S ynchronization of mirror position changes with collection of Spectroelectrochemical f

sample spectra Vessel Volume 7.5 mL lectance • Tailor-made, predefined experiments Spectroelectrochemical • “Hands-free” operation Vessel Material PTFE or PEEK

O r d e r i n g I n fo r m a t i o n

P a r t N u m b e r D e s c r i p t i o n 013-11XX VeeMAX III Includes sample masks (2”, 5/8” and 3/8”), gold substrate alignment mirror, FTIR base mount, and purge tubes 013-12XX Automated VeeMAX III Includes controller, cabling, sample masks (2”, 5/8” and 3/8”), gold substrate alignment mirror, FTIR base mount, and purge tubes Note: Replace XX with your spectrometer’s Instrument Code listed on page 191.

VeeMAX III Sampling Options P a r t N u m b e r D e s c r i p t i o n AutoPRO Software configured for the 090-1000 Manual Polarizer, ZnSe VeeMAX III with automated polarizer. P

090-1200 Manual Polarizer, KRS-5 i k

090-3000 Precision Manual Polarizer, ZnSe e

A spectroelectrochemical cell option for the VeeMAX III is also T

090-3200 Precision Manual Polarizer, KRS-5 n h c e available. The cell allows for specular experiments using a flat IR 090-5000 Precision Automated USB Polarizer, ZnSe window or CaF2 prism, where the beam reflects off the working

electrode or for ATR experiments where often the ATR crystal 090-5100 Precision Automated USB Polarizer, KRS-5 o l

serves as the working electrode. Windows and ATR crystals are Note: Automated version includes PIKE Technologies AutoPRO software and o removable. The electrochemistry cell is equipped with a precision controller. More polarizer options are found in the polarizer section of this catalog. s e i g micrometer for electrode positioning. For an out-of-the-box

spectroelectrochemistry cell for ATR-SEIRAS, see the Jackfish cell in VeeMAX III Replacement Parts the ATR section. P a r t N u m b e r D e s c r i p t i o n w w w 013-4010 Specular Mask Set

300-0002 Gold Substrate Alignment Mirror, 1.25 x 3.0” . p

Note: Please contact PIKE Technologies for items not described in this list. i k h c e t e Spectroelectrochemical Configurations P a r t N u m b e r D e s c r i p t i o n .

013-3300 Electrochemical Cell – PTFE c o

013-3370 Electrochemical Cell – PEEK m 1 2 7 2 - 4 7 2 - 8 0 6

160-5527 Prism, CaF2, 60 degree 013-3360 Crystal Holder, 60 degree

160-1144 Flat Window, CaF2, 20 x 2 mm 160-1304 Flat Window, ZnSe, 20 x 2 mm 013-3320 Flat Window Holder Notes: The electrochemical configuration requires Electrochemical Cell and VeeMAX III specular reflectance accessory. Must select one or more windows. Choose appropriate window holder. More window types for specular reflectance Electrochemical Cell assembly for VeeMAX III. measurements may be found in our listing of transmission windows, 20 x 2 mm. Electrodes supplied by the end-user. See VeeMAX III with ATR and Jackfish cell product sheets for full ATR crystal and configuration options. 64 65 Thin Films and More Beam path within the 10Spec specular reflectance accessory. •  •  •  •  •  •  SampleReflectivityMeasurements 10Spec –Near-normal Extended Height10Spectoaccommodate largesamples interferences Purge cover atmospheric andpurgetubesfor removal of 2”,5/8”and3/8” Sampling masksizesof fixed at 10degrees Sample illumination usingcollimated beamprecisely incidence of angle Fixed 10degree Measure sample reflectance F s e r u t a e

10Spec (left) and Extended Height Standard 10Spec (above) too large to fit within the confinements of the sample compartment. too large to fit within the confinements Extended Height 10Spec is designed to accommodate samples that are the FTIR instrument. The which positions the sample above the top of is 118-mm tall whereas the Extended Height 10Spec is 205-mm tall, reflecting materials. and other coated surfaces, reflecting and non- anti-reflective (AR) reflecting optics, devices, including military surfaces wide variety of glass. It may a also be used to measure near-normal reflectivity of optics are enclosed to allow for purging. angle,on reflectivity are the polarization minimized. The effects design. At a near-normal produced by a focused beam accessory angles incidence and not an average of angle of uniform 10 degree sample area such that the reflectivity measurement is made at a sample reflectivity. It produces a collimated beam to illuminate the designed to make high-performance measurements of accessory The PIKE Technologies 10Spec is an optimized specular reflectance FTIR spectrum measuring the reflectively of glass with the 10Spec. P 10 Note: Replace 010-11XX 010-10XX P 300-0002 010-3010 t r a t r a Dimensions (WxDH) Optics S O S p N N The 10Spec is recommended to measure the reflectivity of The 10Spec is recommended to measure the reflectivity of The 10Spec is available The standard version in two versions. ec p g n i r e d r r e b m u r e b m u i c e

R Angle ofIncidence FTIR Compatibility e f Extended Height XX with your spectrometer’s Instrument Code listed on page 191. p

i t a c i lacement Sample Masks Purge Sealing D D Gold Substrate AlignmentMirror, 1.25x3.0” Specular MaskSet alignment mirrorandFTIRbasemount and3/8”),goldsubstrate (2”,5/8” Includes 3samplemasks Extended Height10SpecAccessory alignment mirrorandFTIRbasemount and3/8”),goldsubstrate (2”,5/8” Includes 3samplemasks SpecularReflectance Accessory 10Spec –10Degree i r c s e i r c s e

Standard I n o p p o i t o i t O F s n P n n i t a m r arts Most, specifymodelandtype 159 x90205mm(excludesbaseplate) 159 x90118mm(excludesbaseplate) Purge tubesandpurgebarbincluded 2”, 5/8”and3/8”” 10 degrees All reflective

and o n

S am p ling O p ti o ns 30Spec and 45Spec – Specular Reflectance for Thick Films

The PIKE Technologies 30Spec is ideal for the measurement of S

relatively thick films by specular reflectance. Samples are simply p

laid across the top of the accessory and the spectrum of the film ecular is measured within a short time period. The 30Spec includes sample masks of 3/8”, 1/4” and 3/16” to define specific sampling areas. The 30Spec provides high-quality FTIR spectra for identification of coatings and can also be used to measure coating thickness. IR throughput is high using the 30Spec due to its relatively simple

optical design. R e f lectance

F e a t u r e s • Measurement of thick films • Measurement of film thickness by specular reflectance • Fixed 30 degree angle of incidence FTIR spectrum of polymer coating on a food container collected using the • Special version – 45Spec for 45 degree angle of incidence PIKE 30Spec. • Sample masks to define sampling area

• Slide-mount design for easy installation of accessory – S p e c i f i c a t i o n s fits all FTIR spectrometers Optics All reflective Angle of Incidence 30 degrees or 45 degrees Sample Masks 3/8”, 1/4” and 3/16” P

Dimensions (W x D x H) 51 x 96 x 77 mm i k

Mount 2 x 3” slide mount e

T n h c e

O r d e r i n g I n fo r m a t i o n o l o P a r t N u m b e r D e s c r i p t i o n s e i g 011-1000 30Spec – 30 Degree Specular Reflectance Accessory

Includes sample masks (3/8”, 1/4”, and 3/16”), alignment mirror and slide-mount 011-4500 45Spec – 45 Degree Specular Reflectance Accessory w w w Optical geometry for the 30Spec. Includes sample masks (3/8”, 1/4”, and 3/16”), alignment mirror and slide-mount . p i

Note: The 30Spec and 45Spec are slide-mount accessories. k h c e t e 30Spec and 45Spec Sampling Options P a r t N u m b e r D e s c r i p t i o n .

011-2010 Sample Masks (3/8”, 1/4”, and 3/16”) c o

300-0039 Aluminum Substrate Alignment Mirror m 1 2 7 2 - 4 7 2 - 8 0 6 Note: Sample masks and alignment mirror fit both 30Spec and 45Spec.

66 67 Thin Films and More Beam path within the 80Spec specular reflectance accessory. •  •  •  •  •  •  for ThinFilms 80Spec –GrazingAngleSpecularReflectance of high-qualityspectra–fitsallFTIRspectrometers of Baseplate mountdesignfor stable operation andcollection todefineuniquesamplingareas version Optional samplemasks Dual polarizermountsfor incomingandoutgoing IRbeam analysis angle grazing Gold-coated reflective optics for highestthroughput incidence of angle Fixed 80degree thinfilmsandmono-molecularlayers Measurement of F s e r u t a e measurement of variations in thin film coatings.measurement of on a sample, and is recommended for smaller samples or for includes three sample version masks to define smaller areas larger, is of ideal for analysis version uniform samples. The second features witha fixedflat This sampling port. sampling surface PIKE Technologies. for positioning optional manual or automated IR polarizers includes polarizer mounts on both incoming and outgoing field vector perpendicular The 80Spec to the sample surface. enhanced by using p-polarized light, with the electric is significantly monolayers, ultra-thin film samples, especially the measurement of the film is collected. Generally and the spectrum of the accessory reflectance.face down across Samples are placed the top of simply thin films andrelatively mono-molecular layers by specular The PIKE Technologies 80Spec is ideal for the measurement of Note: For more polarizer options see the polarizer section of this catalog. P R placing an order. sample compartment width restriction. Please contact PIKE Technologies prior to For compact-size spectrometers, only one polarizer mount may be included due to Notes: Replace 012-11XX 012-10XX P p-polarized IR beam. FTIR spectrum of an ultra-thin film on a reflective substrate using 090-5100 090-5000 090-3200 090-3000 090-1200 090-1000 300-0002 010-3010 t r a t r a e p O lacement N N The 80Spec is available The basic configuration in two versions. g n i r e d r r e b m u r e b m u

XX with your spectrometer’s Instrument Code listed on page 191. D D Precision Automated USBPolarizer, KRS-5 Precision Automated USBPolarizer, ZnSe Precision Manual Polarizer, KRS-5 Precision Manual Polarizer, ZnSe Manual Polarizer, KRS-5 Manual Polarizer, ZnSe Gold Substrate Alignment Mirror, 1.25x3.0” Specular MaskSet mount andFTIRbase Includes agoldsubstratealignmentmirror,dualpolarizer with SampleMasks(2”,5/8”and3/8”) SpecularReflectanceAccessory 80Spec –80Degree mount andFTIRbase Includes agoldsubstratealignmentmirror,dualpolarizer SpecularReflectanceAccessory 80Spec –80Degree P i r c s e i r c s e

arts I n p p o i t o i t O F

and n n i t a m r O p ti o o n ns from beams

AGA – Advanced Grazing Angle Specular Reflectance for Thin Films with Precise Spot Control S p ecular

R Beam path within the AGA – Grazing Angle Specular Reflectance Accessory. e f

The beam from the spectrometer is focused onto the pin lectance mirror. The angle of incidence is equal to 80 degrees. The portion of the beam that is reflected from this mirror is imaged at unit magnification onto the sample, striking it at the same 80 degrees. Thus, the beam at the sample position is uniform and circular in F e a t u r e s dimension – providing excellent quantitative results for the defined sample area. • Quantitative measurement of small areas of thin films and mono-molecular layers • Fixed 80 degree angle of incidence • Measurement of lubricants on hard disks • Sampling dimensions selectable from 1/2”, 3/8”, 1/4”, 3/16” and 1/8” diameter • Polarizer mount for optional polarizer • Baseplate mount design for stable operation and collection of high-quality spectra – fits most FTIR spectrometers • Spectral range 10,000–500 cm-1 P

The PIKE Technologies AGA – Advanced Grazing Angle Specular i k

Reflectance Accessory is a novel instrument designed for quantitative e

measurement of spatially defined areas of thin films on reflective T n h c e substrates. Traditional grazing angle accessories produce a FTIR spectrum of an 18-angstrom thick lubricant on a hard disk sampling area which is elliptical in shape and non-uniformly measured in 15 seconds using an MCT detector. illuminates the sample area. This large asymmetrical sampling o l

area causes problems when quantitative analysis are to be o performed on small sample areas. The Advanced Grazing Angle (AGA) s e i g O r d e r i n g I n fo r m a t i o n Accessory has been designed to overcome this deficiency.

P a r t N u m b e r D e s c r i p t i o n 015-10XX AGA – Grazing Angle Specular Reflectance Accessory Includes 5 selectable spot sizes of 1/2”, 3/8” 1/4”, 3/16” w w w and 1/8”, gold substrate alignment mirror, polarizer

mount and FTIR base mount . p i

Note: Replace XX with your spectrometer’s Instrument Code listed on page 191. k h c e t e Replacement Parts and Sampling Options P a r t N u m b e r D e s c r i p t i o n .

300-0002 Gold Substrate Alignment Mirror, 1.25 x 3.0” c o

090-1000 Manual Polarizer, ZnSe m 1 2 7 2 - 4 7 2 - 8 0 6 Sampling image on a hard disk surface produced by (A) the spatially 090-1200 Manual Polarizer, KRS-5 resolved AGA and (B) a traditional grazing angle accessory. Note: For more polarizer options see the polarizer section of this catalog.

The size and shape of the illuminated spot on the sample is defined by the optics contained in the accessory. The AGA optical design uses primary imaging from one of five user-defined, slide- mounted pin mirrors selectable from 1/2” to 1/8”.

68 69 Thin Films and More by a quick-release mount. with its pinned-in-place mount and the sample is held 180 degrees configurations are selected by rotating easily the sample holder measured value wavenumberat a given or wavelength. The two the a sample is the squareThe absolute reflectanceroot of of the sample twice and the same reference mirror at 12 degrees. from the reference mirror. In the W position it is reflecting from V / W optical arrangement. The beam in the V position reflects which does not require reflectance standards due to its unique PIKE Technologies an Absolute Reflectance Accessory has developed reflectance, which unknown samples could be compared. against Unfortunately, no standards exist today that have guaranteed 100% accurate than measured by other relative specular accessories. have 94–99% reflectance in the infrared region. reflectance is measured these andstandards calculated that against reflectancegold or specular diffuse gold mirror. The sample Sample reflectance measured is usually in comparison to a high- •  •  •  •  Sample Reflectance –Measure Absolute Absolute Reflectance Accessory Dimensions (WxDH) Optics Fixed 12-degree angle of incidence of angle Fixed 12-degree applications testplates inmedical,industrialandmilitary Evaluation of opticalelements Performance of evaluation windowsandmetallicsurfaces surfaces, optical absolute reflectance themeasurement of of For F Sample HolderOpening S Absolute reflectanceeven more measurement has to be s e r u t a e p Optical Configuration i c e Angle ofIncidence FTIR Compatibility f i t a c i Purge Sealing

o s n Most, specifymodelandtype Oval, 40mm(W)x22(H) 165 x241146mm Purge tubesandpurgebarbincluded V /W 12 degrees All reflective

P R Note: Replace  014-10XX P Spectrum of an Si plate measured in the Absolute Reflectance Accessory. Beam path for V and W positions for the Absolute Reflectance Accessory. 300-0061 t r a t r a e p O lacement N N g n i r e d r r e b m u r e b m u Collect Background XX with your spectrometer’s Instrument Code listed on page 191.

D D Gold Substrate Alignment Mirror, 2x3” and FTIRbasemount IncludesV/Wsampleholder,goldsubstratemirror Absolute ReflectanceAccessory Reference V Position P i r c s e i r c s e Mirror

arts I n p p o i t o i t O F

and n n i t a m r

S am o p n ling O Measure Sample p W Position Reference ti Sample Mirror o ns Specular Reflectance – Theory and Applications

Specular reflectance sampling in FTIR represents a very important At the reflective substrate, the beam reflects back to the technique useful for the measurement of thin films on reflective surface of the thin film. When the beam exits the thin film it has

substrates, the analysis of bulk materials and the measurement of geometrically passed through the film twice and is now represented S mono-molecular layers on a substrate material. Often this technique as IA. Infrared energy is absorbed at characteristic wavelengths as p

provides a means of sample analysis with no sample preparation – this beam passes through the thin film and its spectrum is recorded. ecular keeping the sample intact for subsequent measurements. The specular reflectance spectra produced from relatively thin The basics of the sampling technique involve measurement films on reflective substrates measured at near-normal angle of of the reflected energy from a sample surface at a given angle of incidence are typically of high quality and very similar to spectra incidence. The electromagnetic and physical phenomena which obtained from a transmission measurement. This result is expected occur at and near the surface are dependent upon the angle of as the intensity of IA is high relative to the specular component (IR ).

incidence of the illuminating beam, refractive index and thickness of the sample and other sample and experimental conditions. A R

discussion of all of the physical parameters and considerations e surrounding the specular reflectance sampling technique is f beyond the scope of this overview. We will present this technique lectance from an applications-oriented perspective.

Types of Specular Reflectance Experiments • Reflection-absorption of relatively thin films on reflective substrates measured at near-normal angle of incidence • Specular reflectance measurements of relatively thick samples measured at near-normal angle of incidence • Grazing angle reflection-absorption of ultra-thin films or mono- layers deposited on surfaces measured at a high angle of incidence In the case of a relatively thin film on a reflective substrate, the Spectrum of thin film coating on a metal surface measured at 30 degrees specular reflectance experiment may be thought of as similar to a angle of incidence using the VeeMAX III specular reflectance accessory. “double-pass transmission” measurement and can be represented as shown in the following illustration. For relatively thick samples, the specular reflectance experiment produces results which require additional considerations as the specular component of the total reflected radiation is relatively high.

Again, the incident FTIR beam represented by I0 illuminates the sample of a given refractive index (n2 ) and at an angle of incidence θ1. Some of the incident beam is reflected from the P

sample surface, represented by IR at the incident angle θ1. Some i k

of the incident beam is transmitted into the sample represented e

by IT at an angle of θ2. As predicted by Fresnel equations, the T percent of reflected versus transmitted light increases with higher n h c e angles of incidence of the illuminating beam. Furthermore, the

refractive index of the sample, surface roughness, and sample o

absorption coefficient at a given wavelength all contribute to the l o

intensity of the reflected beam. s e i g

Beam path for reflection-absorption of a relatively thin film measured by specular reflection w w w . The incident FTIR beam represented by I0 illuminates the thin p i film of a given refractive index (n2 ) and at an angle of incidence (θ1.). k Some of the incident beam is reflected from the sample surface, h c e t e represented by IR at the incident angle θ1 and is also known as the specular component. Some of the incident beam is transmitted . into the sample represented by IT at an angle of θ2 – calculated c o

from Snell’s Law. m 1 2 7 2 - 4 7 2 - 8 0 6

n1sinθ1 = n2sinθ2

Beam path for a relatively thick sample measured by specular reflection

70 71 Thin Films and More magnetic field oriented in the plane of the incident and reflected radiation. Grazing angle specular reflection analysis produces a strong electro- the reflecting radiation is not enhanced. netic field of the electromag incidence. The perpendicular component of angle of and reflectedgreatly radiation increased is to a near-normalrelative the incident the electromagnetic field in the planeof 85 degrees, incidence, between 60 and incidence. At high angles of angle of thin films andrelatively mono-molecular layersgrazing at ment of is very similar to a transmission spectrum of the polymer polyethylene. has been transformed using the Kramers-Kronig software algorithm and at 30 degrees angle of incidence using the VeeMAX III; the lower spectrum Spectrum (upper – original) of a relatively thick polymer sample measured in the example below. to a transmission-like conversion spectrumKramers-Kronig as shown This specular reflection spectrum can be transformed using the results in index a dispersion spectrum bands. with derivative-shaped spectrum with the the extinction coefficient refractive position of the sample increases.absorption, The super- the reflectivity of Our third application of specular reflectanceOur third is the measureapplication of At wavelengths where the sample exhibits a strong IR -

-

and p-polarization; the FTIR was equipped with an MCT detector. deposited on a gold-surfaced mirror using the PIKE VeeMAX III at 80 degrees Grazing angle specular reflection analysis of a thiol mono-molecular layer thereby producing a stronger absorbance spectrum. the electromagnetic field at the sample surface, of enhanced portion incidence with examine p-polarization,the we only angle of grazing improvesgreatly the sampling result. By collecting the spectrum at an IR polarizer angle measurements, for the grazing use of surface specular reflectance accessories to perform these analyses. preparation is preferred. PIKE Technologies a complete line of offers films on materials andreflective for bulk materials where no sample thin films on substrates,reflective thick for of relatively the analysis Specular reflectance is a valuable FTIR sampling technique for the electromagnetic field at the the orientation of Because of