Here, we use a polymer stabilizer to prepare metal-organic framework (MOF) suspensions that exhibit markedly decreased scatter in their ground-state and transient absorption spectra. With these MOF suspensions, the protocol provides various guidelines to characterize the MOFs spectroscopically to yield interpretable data.
Metal-organic frameworks (MOFs) offer a unique platform to understand light-driven processes in solid-state materials, given their high structural tunability. However, the progression of MOF-based photochemistry has been hindered by the difficulty in spectrally characterizing these materials. Given that MOFs are typically larger than 100 nm in size, they are prone to excessive light scatter, thereby rendering data from valuable analytical tools like transient absorption and emission spectroscopy nearly uninterpretable. To gain meaningful insights of MOF-based photo-chemical and physical processes, special consideration must be taken toward properly preparing MOFs for spectroscopic measurements, as well as the experimental setups that garner higher quality data. With these considerations in mind, the present guide provides a general approach and set of guidelines for the spectroscopic investigation of MOFs. The guide addresses the following key topics: (1) sample preparation methods, (2) spectroscopic techniques/measurements with MOFs, (3) experimental setups, (3) control experiments, and (4) post-run stability characterization. With appropriate sample preparation and experimental approaches, pioneering advancements toward the fundamental understanding of light-MOF interactions are significantly more attainable.
Metal-organic frameworks (MOFs) are composed of metal oxide nodes linked by organic molecules, that form hierarchical porous structures when their constituent parts react together under solvothermal conditions1. Permanently porous MOFs were first reported in the early 2000s, and since then, the burgeoning field has expanded to encompass a wide range of applications, given the unique tunability of their structural components2,3,4,5,6,7. During the growth of the field of MOFs, there have been a handful of researchers that have incorporated photoactive materials into the nodes, ligands, and pores of MOFs to harness their potential in light-driven processes, like photocatalysis8,9,10,11, upconversion12,13,14,15,16, and photoelectrochemistry17,18. A handful of the light-driven processes of MOFs revolve around energy and electron transfer between donors and acceptors17,19,20,21,22,23,24,25. The two most common techniques used to study energy and electron transfer in molecular systems are emission and transient absorption spectroscopy26,27.
A great deal of research on MOFs has focused on emission characterization, given the relative ease in preparing samples, performing measurements, and (relatively) straightforward analysis19,22,23,24,28. Energy transfer typically manifests itself as a loss in the donor emission intensity and lifetime and an increase in the emission intensity of the acceptor loaded into the MOF backbone19,23,28. Evidence of charge transfer in a MOF manifests as a decrease in emission quantum yield and lifetime of the chromophore in the MOF29,30. While emission spectroscopy is a powerful tool in the analysis of MOFs, it only addresses part of the necessary information to present a complete mechanistic understanding of MOF photochemistry. Transient absorption spectroscopy can not only provide support for the existence of energy and charge transfer, but the method can also detect spectral signatures associated with the non-emissive singlet and triplet excited state behaviors, making it one of the most versatile tools for characterization31,32,33.
The primary reason why more robust characterization techniques like transient absorption spectroscopy are seldom applied toward MOFs is due to the difficulty in preparing samples with minimal scatter, especially with suspensions34. In the few studies successfully performing transient absorption on MOFs, the MOFs are <500 nm in size, with some exceptions, stressing the importance of reducing particle size to minimize scatter15,21,25,35,36,37. Other studies make use of MOF thin films17 or SURMOFs38,39,40 to circumvent the scatter issue; however, from an applicability stand-point, their use is quite limited. Additionally, some research groups have taken to making polymer films of MOFs with Nafion or polystyrene34, the former raising some concerns for stability given the highly acidic sulfonate groups on Nafion. Gaining inspiration from the preparation of colloidal semiconductor suspensions41,42, we have found great success using polymers to help suspend and stabilize MOF particles for spectroscopic measurements11. In this work, we establish widely applicable guidelines to follow when it comes to preparing MOF suspensions and characterizing them with emission, nanosecond (ns), and ultrafast (uf) transient absorption (TA) spectroscopy techniques.
1. Preparation of MOF suspensions using a polymer stabilizer
2. Preparation of filtered MOF suspensions for nanosecond transient absorption measurements (nsTA)
3. Purging the MOF suspension
4. Perpendicular pump-probe nanosecond transient absorption setup (nsTA)
5. Narrow-angle nsTA setup
6. Ultrafast transient absorption measurements (ufTA)
7. Preparation of MOFs for emission measurements
8. MOF emission measurements
The electronic absorption spectra of PCN-222(fb) with and without PNH2 and filtering are shown in Figure 4. The MOF without PNH2 was just tip-sonicated and diluted. When comparing the two spectra, the biggest difference is the minimization of baseline scatter, which shows up as a broad upward absorption with decreasing wavelengths and also broadens the electronic transitions quite noticeably. For further comparison, the PCN-222(fb) ligand in solution, tetracarboxyphenylporphyrin (H2TCPP), is provided in Supplementary Figure 3. An indicator of baseline scatter is an upward absorption in the MOF where the ligand in solution does not absorb. In the case of TCPP, it has no absorption at 800 nm, whereas the MOF without PNH2 shows a clear "absorption" in this region. One issue sometimes faced is finding the appropriate amount of MOF needed to attain a filtered suspension of sufficient absorbance. This is usually a process of trial and error, but if the filtered MOF suspension absorbance does not change over a range of MOF amounts, then using a syringe filter with slightly larger pores usually works.
Emission measurements of tip-sonicated PCN-222(fb) without PNH2 and H2TCPP in DMF were performed and are shown in Figure 5. Without the use of PNH2, the excitation and emission spectra of PCN-222(fb) and H2TCPP in DMF align quite well, indicating PNH2 is not necessary for these measurements. In our prior work, we attribute the differences in emission lifetimes (Figure 5C) between PCN-222(fb) (1.5 ns, 3 ns) and H2TCPP (4 ns, 12 ns) to energy transfer quenching processes between protonated and unprotonated H2TCPP linkers in the MOF11. If the PNH2 suspension protocol is employed for emission measurements, the PNH2 will emit in the visible region ( = 475 nm), highlighting its primary setback. Depending on the polymer and concentration, they exhibit absorptions in the UV region and sometimes in the visible region. In the case of PNH2, as shown in Supplementary Figure 4, its absorption onset occurs ca. 450 nm, albeit at a weak level (~0.01 OD). Moreover, when excited by 415 nm light, PNH2 has a broad emission spectrum (Supplementary Figure 5). While PNH2 presents an issue for emission measurements, its involvement with transient absorption measurements is minimal. If a sample needs UV excitation for transient absorption measurements, it is imperative that control experiments with a solution of polymer be performed. In most cases, the polymer TA spectrum (if present) can be subtracted from the MOF spectrum, or their decay lifetimes can be identified within the MOF decay lifetimes. A good rule is keeping the amount of polymer at or below 50 mg per sample.
Both nsTA and ufTA spectra were obtained with MOF suspensions. In Figure 6 are the TA spectra of PCN-222(fb) with and without PNH2, and H2TCPP in solution right after laser excitation at 415 nm (Soret band excitation). As observed in the spectrum of PCN-222(fb) without PNH2, there is a substantial amount of scatter present, causing the TA spectrum to become increasingly negative with decreasing wavelength. The non-PNH2 TA spectrum (Figure 6A) is in stark contrast to the spectrum of H2TCPP in solution and is a cause for concern. Moreover, the kinetics of H2TCPP and PCN-222(fb) without PNH2 are starkly different (Figure 7). Looking at the spectrum of PCN-222(fb) with PNH2, both the lifetimes and spectra align much better with the H2TCPP TA spectrum11. To gain a complete photophysical picture, a quality initial TA spectrum of the MOF needs to be obtained, along with kinetics at the ground-state bleach (negative signal) and excited state absorptions (positive signal) to see if they agree with one another. Additional measurements using the narrow-angle nsTA setup are presented in Supplementary Figure 6. Comparing the nsTA spectra of PCN-222(fb) between both experimental setups shows a moderate improvement in signal at lower power densities with the narrow-angle setup. Looking at the ufTA spectrum of PCN-222(fb) with PNH2, there is a close resemblance to the linker in solution (Figure 8), showing a ground-state bleach at ~420 nm and excited-state absorptions on either side of the bleach. With both the nsTA and ufTA measurements of PCN-222(fb) with PNH2 in good agreement with H2TCPP in solution, we therefore conclude the observed signal is from the MOF and not due to scatter. After measurements, the absorption spectrum of PCN-222(fb)+PNH2 was remeasured (Supplementary Figure 7) and looked nearly identical to the initial spectrum, indicating minimal degradation throughout the experiment. For further confirmation of any degradation, the MOF suspension can be passed through a 20 nm syringe filter (Table of Materials), and the consequent UV-Vis spectrum of the filtrate should have minimal absorbances from the MOF linker, which would otherwise indicate degradation.
Control experiments and literature on the ligand in solution are key factors when analyzing MOF TA spectra. The broad negative signal observed in MOF TA spectra should be taken as a universal sign that there is excessive scatter occurring from the MOF. Additionally, when looking at the kinetic profile of MOFs with excess scatter arising from both the pump and probe beams, the scatter does not just decay within the instrument response function (IRF; usually the pulse width of the laser); it can have lifetimes up to microseconds that mask the true kinetic decay, however the reason behind this behavior is largely unexplored in the MOF community (Figure 7A). The main takeaway is that, if the signal is broadly negative and the lifetimes are not like those of the ligand (there are exceptions), then the data is not worth interpretation.
Figure 1: Simplified schematic of a perpendicular pump-probe nsTA setup (Table of Materials). P1-P3 are the quartz directional/alignment prisms; CCM1,2 are directional concave mirrors to guide the probe beam; SC1 is the 1 cm sample cuvette used in nsTA measurements; SM1 is the sample mount provided by the spectrometer manufacturer; BD is a beam dump (optional); FL is a focusing lens provided by the instrument manufacturer. To align the pump laser (Actinic Pump) with the probe beam in the sample chamber, the intracavity prism (P3) must be adjusted. All other optics are stationary. Please click here to view a larger version of this figure.
Figure 2: Simplified schematic of a narrow-angle pump-probe nsTA setup (Table of Materials). P1-P3 are the quartz directional/alignment prisms; CCM1,2 are directional concave mirrors to guide the probe beam; SC1 is the 1 cm sample cuvette used in nsTA measurements; SM1 is the sample mount provided by the spectrometer manufacturer; BD is a beam dump (optional); FL is a focusing lens provided by the instrument manufacturer; CCL is a biconcave lens; CVL is a plano-convex lens; MM1-3 are directional mini mirrors to guide the pump beam to the sample cell; SC2 is a 2 mm path length sample cell; SM2 is a clamping sample mount used in ufTA measurements as well. The key factors needed to align the pump and probe beams are proper placement of the pump beam on mirrors MM1-3 and SC2, while SC2 remains at the focal point of the probe beam. Please click here to view a larger version of this figure.
Figure 3: Simplified schematic of the ultrafast transient absorption setup (Table of Materials) used to characterize MOFs. OPA is the optical parametric amplifier used to generate the pump source; ufND is the ND filter wheel used to attenuate the incoming pump power; TS is the telescope used to focus the pump beam; ufM is the kinematic mirror that directs the incoming pump beam onto the sample cell and aligns the pump beam with the probe beam; SC2 is the 2 mm path length sample cell for ufTA measurements; ufSM is a clamping sample mount used in ufTA measurements. The key to aligning pump and probe beams for MOF measurements is first aligning the beams with a dissolved standard sample. Please click here to view a larger version of this figure.
Figure 4: Steady-state absorption spectra of tip-sonicated PCN-222(fb) without PNH2 (black trace), with PNH2 and filtration (red trace), and the absorption spectrum of H2TCPP (MOF linker) shown as the blue trace. The solvent was DMF. A key indicator of scatter is a broad upward absorption underneath the true sample absorption spectrum, as shown in the absorption spectrum of PCN-222(fb) without PNH2. Conversely, the sample with PNH2 barely exhibits an upward absorption. Please click here to view a larger version of this figure.
Figure 5: Emission spectra. (A) Emission spectra of tip-sonicated and diluted PCN-222(fb) (green trace) and H2TCPP (MOF ligand; blue trace); (B) Excitation spectra of tip-sonicated and diluted PCN-222(fb) (green trace) and H2TCPP (MOF ligand; blue trace) measured at 720 nm; (C) Time-correlated single photon counting (TCSPC) decay traces of PCN-222(fb) (green trace) and H2TCPP (blue trace) measured at 650 nm. The kinetic fits are the red traces. The solvent was DMF and the excitation wavelength for both spectral and TCSPC emission measurements was 415 nm. The emission and excitation spectra of PCN-222(fb) and H2TCPP align closely with one another, and the kinetic profiles of H2TCPP and PCN-222(fb) are comparable as well. Prior work attributed the shortening of the lifetimes in PCN-222(fb) (1.5 ns, 3 ns) compared to H2TCPP (4 ns, 12 ns) to energy transfer quenching from unprotonated MOF linkers (long lifetime component) to protonated linkers (short lifetime component) that act as energy traps11. This figure has been adapted with permission from Benseghir et al.11. Please click here to view a larger version of this figure.
Figure 6: Nanosecond TA spectra. The spectra of tip-sonicated PCN-222(fb) (A) without PNH2, (B) with PNH2 and filtration, and (C) H2TCPP (MOF ligand) in DMF. λex = 415 nm, 3 mJ·cm-2. Similar to the ground-state absorption spectrum of PCN-222(fb) without PNH2, the TA spectrum also shows a broad "absorbance" feature from 450-800 nm attributed to scatter. Comparatively, the TA spectrum of PNH2@PCN-222(fb) resembles that of its parent linker H2TCPP, indicating a genuine TA signal from the MOF. This figure has been adapted with permission from Benseghir et al.11. Please click here to view a larger version of this figure.
Figure 7: nsTA kinetic decay traces and their fits (red traces). (A) Tip-sonicated PCN-222(fb) without PNH2 at the ground-state bleach (GSB; 420 nm) and excited state absorption (ESA; 385 nm), (B) tip-sonicated and filtered PCN-222(fb) with PNH2 at 419 nm and 470 nm, and (C) H2TCPP (MOF ligand) at 420 nm and 470 nm in DMF. λex = 415 nm, 3 mJ·cm-2. Compared to PCN-222(fb), the kinetic decays of PNH2@PCN-222(fb) align with the time profile of H2TCPP much better. We attribute the decay kinetics observed in PCN-222(fb) to scatter from both the probe and pump beams. It is important to note that scatter can often produce kinetics not just limited to the instrument response time, but additional decays extending into the microsecond region. This figure has been adapted with permission from Benseghir et al.11. Please click here to view a larger version of this figure.
Figure 8: ufTA spectral time mappings (2 ps-3 ns; purple to crimson). (A) Tip-sonicated PCN-222(fb) with PNH2 and (B) the MOF linker H2TCPP in DMF. λex = 400 nm, 50 µJ·cm-2. All the ufTA spectra bear similar features, indicating a genuine signal produced by the MOF. In the case of PCN-222(fb), the spectral changes are more pronounced than the linker alone, which are likely attributed to the quenching of the excited singlet state by efficient energy transfer to protonated H4TCPP centers in the MOF, as well as some energy transfer to the PNH2 suspending agent. The protonated MOF linkers arise from the acidic synthetic conditions needed to make the MOF. Please click here to view a larger version of this figure.
Supplementary Figure 1: Schematic of the ufTA sample chamber when determining the pump laser spot size. ufND is the ND filter wheel used to attenuate the incoming pump power; TS is the telescope used to focus the pump beam; ufM is the kinematic mirror that directs the incoming pump beam onto the sample cell and aligns the pump beam with the probe beam; PHW is the circular pinhole wheel with various hole diameters (Table of Materials); PWR is the power meter used to measure the power at decreasing pinhole sizes. We stress that the pinhole wheel needs to be at the focal point of the pump beam to get accurate spot sizes. Please click here to download this File.
Supplementary Figure 2: Schematic of the fluorimeter used for MOF emission measurements. SC1 is a 1 cm path length sample cell (Table of Materials); FO1 are the excitation wavelength focusing optics; FO2 are the TCSPC (time-correlated single photon counting) LED focusing optics; PMT is a photomultiplier tube for spectral emission measurements. Please click here to download this File.
Supplementary Figure 3: Absorption spectrum of H2TCPP in DMF. The strong absorption at 420 nm is an S0→S2 transition (Soret band), and four vibronic transitions from 500-700 nm are S0→S1 transitions (Q-bands). Please click here to download this File.
Supplementary Figure 4: Absorbance spectrum of PNH2 in DMF. Absorbance onset occurs at ~450 nm. Please click here to download this File.
Supplementary Figure 5: Emission spectrum of PNH2 in DMF when excited by 415 nm light. Because PNH2 fluoresces, we often refrain from using it during emission measurements. Please click here to download this File.
Supplementary Figure 6: Nanosecond TA spectra of tip-sonicated and filtered PCN-222(fb) using a narrow-angle pump-probe setup (see Figure 2 for the schematics). Compared to the conventional perpendicular pump-probe setup, the narrow-angle setup shows a noticeable increase in signal and signal-to-noise ratio using lower pump energies (1 mJ·cm-2). λex = 415 nm. Please click here to download this File.
Supplementary Figure 7: Absorption spectrum of PCN-222(fb)+PNH2. The absorption spectrum before nsTA measurements (red trace), after nsTA measurements (blue trace), and the 20 nm MOF filtrate after nsTA measurements (green trace), indicating little sample degradation over the course of the experiment. This figure has been adapted with permission from Benseghir et al.11. Please click here to download this File.
While the above results and protocol delineate general guidelines for minimizing scatter from MOFs in spectroscopic characterization, there is a wide variability in MOF particle size and structure that impacts spectroscopic results, and therefore blurs the methods of interpretation. To help clarify interpretation and ease the strain that comes with analyzing MOF spectroscopic data, finding a procedure to make the MOFs as small as possible is key. This is a limiting factor for most spectroscopy-related analyses of MOFs. Before any further preparations are done, the MOF particle size is a critical factor that needs to be considered. A fantastic starting point is looking for synthetic procedures of MOFs used in photodynamic therapy4,43,44,45.
When preparing the MOF suspensions, there are a few caveats that need to be addressed. We commonly employ PNH2 as a suspension stabilizer because it is soluble in a range of typical solvents and absorbs minimally in the UV-visible range; however, depending on certain solvents, other polymers may be more suitable (PEG, PVA, etc.). It is at the user's discretion to find a suitable polymer for their solvent system. Moreover, the molecular number/weight of the polymer is kept low to prevent difficulties in the filtration process. When using a tip sonicator, the less time spent sonicating the better. Tip sonication is a much more aggressive method than bath sonication, and longer sonication times/higher amplitudes (>20 min, >30%) can potentially degrade materials46,47. A good test for determining degradation is passing the suspension through a 20 nm filter, so that only molecules will pass through, and checking the absorption spectrum of the remaining solvent. Determining optimal sonication times/intervals/amplitudes is usually a process of trial and error; however, the aforementioned protocol is a good starting point. We recommend using bath sonication first to see if adequate suspensions can be made.
When passing the suspension through a syringe filter, 200 and 400 nm pore size syringe filters are typically used. If the MOF particle sizes are closer to 1 µm in size, then a 400 nm syringe filter is generally used to pass more MOF through the filter. This choice gives rise to a bit more scatter in the TA spectrum but does not impact the data appreciably. Additionally, MOFs can tend to aggregate on the syringe filter, preventing more MOF from passing through it. To combat this, a small portion of MOF is passed through the filter, the syringe is drawn back a bit (pulling aggregated MOF on the filter back into the syringe in the process), and then the syringe plunger is pushed back toward the filter, pushing more MOF out in the process. This method is repeated until there is no suspension left in the syringe.
While MOFs can be considered more robust than their constituent ligands in solution, there are limitations on the power/energy levels that are used in transient absorption experiments. We stress the importance of performing linearity checks in ufTA measurements and spot size measurements for both ufTA and nsTA measurements. These measurements ensure that no non-linear effects are present during measurements and minimize the amount of sample degradation. Additionally, we stress the need to perform the aforementioned control experiments. Narrow-angle nsTA measurements are really a "last resort" and only necessary if the MOF TA signal is weak (<10 mOD) and if the sample signal is scattered too much in a 1 cm path length cell. Employing a smaller path length cuvette and smaller beam size helps minimize the scatter accrued along the light path.
There are a couple of notes for fluorescence measurements. For solution-state measurements, typically, an OD of 0.1 is used at the excitation wavelength to minimize reabsorption effects. Reabsorption is present in the fluorescence spectra when the signal is weak and hypsochromically-shifted compared to dilute solutions. For MOFs, the OD at the excitation wavelength is variable due to baseline scatter. Sometimes, an OD of 0.1-0.2 provides a sufficient signal. We recommend adjusting the concentration until reabsorption effects are present in the MOF fluorescence spectrum and then diluting until an adequate signal is obtained without such effects.
With the guidelines established in this work, we aim to alleviate some of the present burdens that come with performing spectroscopy measurements on MOFs. Given the ease of the protocol for preparing MOF suspensions, it can be broadly modified to cater to a given researcher's desired specifications. With the growing plethora of photoactive MOFs in the literature, the ability to ascertain a deep understanding of the light-driven processes that govern MOF photochemistry is more viable. We predict that the preparative techniques established in this work will not only help drive progress in the field of MOF photochemistry, but will also carry over into other fields that work with inherently scatter-prone solid-state materials.
The authors have nothing to disclose.
This work was supported by the Department of Energy under Grant DE-SC0012446.
1 cm cuvette sample mount (SM1) | Edinburgh Instruments | n/a | Contact company |
1 mL disposable syringes | EXELINT | 26044 | |
10 mL disposable syringes | EXELINT | 26252 | |
1-dram vials | FisherSci | CG490001 | |
20 nm syringe filters | VWR | 28138-005 | The filters are made by Whatman/Cytiva, and their catalog number is 6809-1002 |
200 nm syringe filters | Cytiva, Whatman | 6784-1302 | |
Absorption spectrophotometer | Agilent | Cary 5000 Spectrophotometer | Contact company |
Acetronitrile (ACN) | FisherSci | AA36423 | |
Ar gas tank | Linde/PraxAir | P-4563 | |
bis amino-terminated polyethylene glycol (PNH2) | Sigma-Aldrich | 452572 | MOF suspending agent |
Clamping sample mount for nsTA (SM2) | Ultrafast Systems | n/a | Contact company |
Concave lens for telescope(CCL1) | Thorlabs | LD1613-A-ML | |
Convex lens for telescope (CVL1) | Thorlabs | LA1708-A-ML | |
Custom 1 cm optical cell with 24/40 outer joint | QuarkGlass | QSE-1Q10-2440 (Spectrosil Cat #1-Q-10 | We requested the 1 cm cell to have a joint |
Custom 2mm optical cell with 14/20 outer joint | QuarkGlass | QSE-1Q2-1420 (Spectrosil Cat # 1-Q-2) | We requested the 2 mm cell to have a joint |
Dimethylformamide (DMF) | FisherSci | D119 | |
Dye laser (Nd:YAG pumped) for 415 nm output | Sirah | CobraStretch | |
Dye laser dye, Exalite 417 | Luxottica | 4170 | |
Femtosecond laser | Coherent | Astrella | |
Fluorimeter | Photon Technology Inc. (Horiba) | QuantaMaster QM-200-4E | |
Fluorimeter arc lamp, 75 W | Newport | 6251NS | |
Fluorimeter PMT | Hamamatsu | 1527 | |
Fluorimeter Software | PTI/Horiba | FelixGX | |
Fluorimeter TCSPC Module | Becker & Hickl GmbH | PMH-100 | |
lens mounts for telescope | Thorlabs | LMR1 | |
Long purging needles | STERiJECT | PRE-22100 | |
Magnetic stirrer | Ultrafast Systems | n/a | Contact company |
mirror 1 (MM1) 350-700 nm | Newport | 10Q20BB.1 | |
MM1 mount | Thorlabs | KM100 | |
MM1 post | Thorlabs | TR2 | |
MM1 post holder | Thorlabs | PH1.5 | |
MM2 mount | Thorlabs | MFM05 | |
MM2,3 mirrors | thorlabs | BB03-E02 | |
MM2,3 post | Thorlabs | MS3R | |
MM2,3 post bases | Thorlabs | MBA1 | |
MM2,3 post holders | Thorlabs | MPH50 | |
MM3 mount | Thorlabs | MK05 | |
mounting posts for telescope optics | Thorlabs | TR4 | |
Nanosecond TA Nd:YAG lasers | Spectra-Physics | QuantaRay INDI Nd:YAG | |
Nanosecond TA spectrometer | Edinburgh Instruments | LP980 | |
nsTA ICCD camera | Oxford Instruments | Andor iStar ICCD camera | Contact company |
nsTA PMT | Hamamatsu | R928 | |
Optical parametric amplifier | Ultrafast Systems | Apollo | |
Parafilm | FisherSci | S37440 | |
Pinhole wheel | Thorlabs | PHW16 | |
Pinhole wheel post base | Thorlabs | CF125C | |
Pinhole wheel post holder | Thorlabs | PH1.5 | |
Pinhole wheel post/mount assembly | Thorlabs | NDC-PM | |
post bases for telescope optics | Thorlabs | CF125C | |
post holders for telescope optics | Thorlabs | PH4 | |
Power detector for ns TA | Thorlabs | S310C | |
Prism assembly (P2,3) | Edinburgh Instruments | n/a | Contact company |
Prism mount (P1) | OWIS | K50-FGS | |
Prism post (P1) | Thorlabs | TR4 | |
Prism post base (P1) | Thorlabs | CF125C | |
Prism post holder (P1) | Thorlabs | PH4 | |
Quartz prisms (P1-P3) | Newport | 10SR20 | |
Rubber outer joint septa (14/20) | VWR | 89097-540 | |
Rubber outer joint septa (24/40) | ChemGlass | CG-3022-24 | |
Sonication tip | Branson | product discontinued | Closest alternative is 1/8" diam. tip from iUltrasonic |
Square ND filters | Thorlabs | NEK01S | |
Stir bars | StarnaCells/FisherSci | NC9126395 | |
Thorlabs power detector for ufTA | Thorlabs | S401C | |
Thorlabs power meter | Thorlabs | PM100D | |
Tip sonicator | Branson | Digital Sonifer 450, product discontinued | Closest alternative is SFX550 from iUltrasonic |
Tygon tubing | Grainger | 8Y589 | |
ufTA ND filter wheel | Thorlabs | NDC-25C-2-A | |
ufTA ND filter wheel mount | Thorlabs | NDC-PM | |
ufTA ND filter wheel post | Thorlabs | PH2 | |
ufTA ND filter wheel post base | Thorlabs | CF125C | |
ufTA pump alignment mirror | Thorlabs | PF10-03-F01 | |
Ultrafast TA telescope assembly | Ultrafast Systems | n/a | Contact company |
Ultrafast transient absorption spectrometer | Ultrafast Systems | HeliosFire | |
Xe arc probe lamp | OSRAM | 4050300508788 |