Djavani-Tabrizi, I., Yuan, Z., Lindkvist, T. T., Xing, J., Chen, L. & Nielsen, S. B. (2025). Gas-Phase Fluorescence Excitation Experiments on Cryogenically Cold Rhodamine B Cations Linked to Various Amino Acid Esters. Journal of The American Society for Mass Spectrometry, 36(2), 409-415. https://doi.org/10.1021/jasms.4c00469

Lindkvist, T. T., Sillesen, C., Klinkby, N., Jensen, H. H., Andersen, L. H. & Nielsen, S. B. (2025). Photophysics of a Methylated GFP Chromophore Anion in Vacuo. Journal of Physical Chemistry A, 129(19), 4245–4251. https://doi.org/10.1021/acs.jpca.5c02039

Lindkvist, T. T., Djavani-Tabrizi, I., Andersen, L. H. & Nielsen, S. B. (2025). Turning on the Fluorescence from Isolated GFP Chromophore Anions at Cryogenic Temperatures. Physical Review Letters, 134(9), Artikel 093001. https://doi.org/10.1103/PhysRevLett.134.093001

Lindkvist, T. T., Kjær, C., Langeland, J., Vogt, E., Kjaergaard, H. G. & Nielsen, S. B. (2024). Absorption and fluorescence spectroscopy of cold proflavine ions isolated in the gas phase. Journal of Chemical Physics, 160(18), Artikel 184306. https://doi.org/10.1063/5.0204331

Lindkvist, T. T., Langeland, J., Kjær, C. & Nielsen, S. B. (2024). Empirical Calibration of a Cylindrical Ion Trap for Mass-Selected Gas-Phase Fluorescence Spectroscopy. Journal of The American Society for Mass Spectrometry, 35(1), 123-130. https://doi.org/10.1021/jasms.3c00349

Toft Lindkvist, T., Djavani-Tabrizi, I., Chen, L. & Brøndsted Nielsen, S. (2024). Freezing Conformers for Gas-Phase Förster Resonance Energy Transfer. ChemPlusChem, 89(12), Artikel e202400448. https://doi.org/10.1002/cplu.202400448

Langeland, J., Lindkvist, T. T., Kjær, C. & Nielsen, S. B. (2024). Gas-phase Förster resonance energy transfer in mass-selected and trapped ions. Mass Spectrometry Reviews, 43(3), 477-499. https://doi.org/10.1002/mas.21828

Djavani-Tabrizi, I., Lindkvist, T. T., Langeland, J., Kjær, C., Graham, M., Kjaergaard, H. G. & Nielsen, S. B. (2024). Tautomer-Selective Fluorescence Spectroscopy of Oxyluciferin Anions. Journal of the American Chemical Society, 146(39), 26975-26982. https://doi.org/10.1021/jacs.4c08596

Langeland, J., Christensen, N. F., Vogt, E., Kjær, C., Lindkvist, T. T., Nielsen, S. B. & Kjaergaard, H. G. (2023). Cryogenic Absorption and Emission Spectroscopy of the Oxyluciferin Anion In Vacuo. Journal of Physical Chemistry Letters, 14(25), 5949-5954. https://doi.org/10.1021/acs.jpclett.3c01206

Kjær, C., Vogt, E., Langeland, J., Christensen, N. F., Lindkvist, T. T., Kjaergaard, H. G. & Nielsen, S. B. (2023). Cryogenic fluorescence spectroscopy of oxazine ions isolated in vacuo. Physical Chemistry Chemical Physics, 25(47), 32715-32722. https://doi.org/10.1039/d3cp04615j

Kjær, C., Vu-Phung, A., Toft Lindkvist, T., Langeland, J. & Brøndsted Nielsen, S. (2023). Cryogenic Ion Fluorescence Spectroscopy: FRET in Rhodamine Homodimers and Heterodimers. Chemistry - A European Journal, 29(60), Artikel e202302166. https://doi.org/10.1002/chem.202302166

Ashworth, E. K., Stockett, M. H., Kjær, C., Bulman Page, P. C., Meech, S. R., Nielsen, S. B. & Bull, J. N. (2022). Complexation of Green and Red Kaede Fluorescent Protein Chromophores by a Zwitterion to Probe Electrostatic and Induction Field Effects. The Journal of Physical Chemistry A, 126(7), 1158-1167. https://doi.org/10.1021/acs.jpca.1c10628

Ashworth, E. K., Langeland, J., Stockett, M. H., Lindkvist, T. T., Kjær, C., Bull, J. N. & Nielsen, S. B. (2022). Cryogenic Fluorescence Spectroscopy of Ionic Fluorones in Gaseous and Condensed Phases: New Light on Their Intrinsic Photophysics. The Journal of Physical Chemistry A, 126(51), 9553-9563. https://doi.org/10.1021/acs.jpca.2c07231

Kjær, C., Langeland, J. & Nielsen, S. B. (2022). Intrinsic fluorescence from firefly oxyluciferin monoanions isolated in vacuo. Physical Chemistry Chemical Physics, 24(31), 18505-18510. https://doi.org/10.1039/d2cp02024f

Gruber, E., Teiwes, R., Kjær, C., Brøndsted Nielsen, S. & Andersen, L. H. (2022). Tuning fast excited-state decay by ligand attachment in isolated chlorophylla. Physical Chemistry Chemical Physics, 24(1), 149-155. https://doi.org/10.1039/d1cp04356k

Kjær, C., Bull, J. N., Carrascosa, E., Nielsen, S. B. & Bieske, E. J. (2021). Action spectroscopy of isomer-selected luciferin anions. European Physical Journal D, 75(3), Artikel 72. https://doi.org/10.1140/epjd/s10053-021-00076-w

Coughlan, N. J. A., Stockett, M. H., Kjær, C., Ashworth, E. K., Bulman Page, P. C., Meech, S. R., Brøndsted Nielsen, S., Blancafort, L., Hopkins, W. S. & Bull, J. N. (2021). Action spectroscopy of the isolated red Kaede fluorescent protein chromophore. Journal of Chemical Physics, 155(12), Artikel 124304. https://doi.org/10.1063/5.0063258

Kjær, C., Langeland, J., Lindkvist, T. T., Sørensen, E. R., Stockett, M. H., Kjaergaard, H. G. & Nielsen, S. B. (2021). A new setup for low-temperature gas-phase ion fluorescence spectroscopy. Review of Scientific Instruments, 92(3), Artikel 033105. https://doi.org/10.1063/5.0038880

Nielsen, S. B. (2021). EDITORIAL: A SPECIAL ISSUE DEDICATED TO THE PROFESSIONAL CONTRIBUTIONS OF EINAR UGGERUD. Mass Spectrometry Reviews, 40(6), 723-724. https://doi.org/10.1002/mas.21655

Vogt, E., Langeland, J., Kjær, C., Lindkvist, T. T., Kjaergaard, H. G. & Nielsen, S. B. (2021). Effect of Freezing out Vibrational Modes on Gas-Phase Fluorescence Spectra of Small Ionic Dyes. Journal of Physical Chemistry Letters, 12(46), 11346-11352. https://doi.org/10.1021/acs.jpclett.1c03259

Giacomozzi, L., Kjær, C., Brøndsted Nielsen, S., Ashworth, E. K., Bull, J. N. & Stockett, M. H. (2021). Non-statistical fragmentation in photo-activated flavin mononucleotide anions. Journal of Chemical Physics, 155(4), Artikel 044305. https://doi.org/10.1063/5.0056415

Zettergren, H., Domaracka, A., Schlathölter, T., Bolognesi, P., Díaz-Tendero, S., Łabuda, M., Tosic, S., Maclot, S., Johnsson, P., Steber, A., Tikhonov, D., Castrovilli, M. C., Avaldi, L., Bari, S., Milosavljević, A. R., Palacios, A., Faraji, S., Piekarski, D. G., Rousseau, P. ... Petrignani, A. (2021). Roadmap on dynamics of molecules and clusters in the gas phase. European Physical Journal D, 75(5), Artikel 152. https://doi.org/10.1140/epjd/s10053-021-00155-y

Zhao, Y., Sørensen, E. R., Lindkvist, T. T., Kjær, C., Brøndsted Nielsen, M., Chen, L. & Brøndsted Nielsen, S. (2021). Triangular Rhodamine Triads and Their Intrinsic Photophysics Revealed from Gas-Phase Ion Fluorescence Experiments. Chemistry - A European Journal, 27(42), 10875-10882. https://doi.org/10.1002/chem.202101322

Kjær, C., Jones, N. C., Stockett, M. H., Hoffmann, S. V. & Nielsen, S. B. (2020). Circular dichroism, anisotropy and absorption spectroscopy of Chlorophyll b in methanol and mixed methanol-water solutions. Physical Chemistry Chemical Physics, 22(46), 26961-26966. https://doi.org/10.1039/D0CP03284K

Kjær, C., Gruber, E., Nielsen, S. B. & Andersen, L. H. (2020). Color tuning of chlorophyll a and b pigments revealed from gas-phase spectroscopy. Physical chemistry chemical physics : PCCP, 22(36), 20331-20336. https://doi.org/10.1039/d0cp03210g

Kjær, C., Hansson, R. F., Hedberg, C., Jensen, F., Jensen, H. H. & Nielsen, S. B. (2020). Gas-phase action and fluorescence spectroscopy of mass-selected fluorescein monoanions and two derivatives. Physical Chemistry Chemical Physics, 22(17), 9210-9215. https://doi.org/10.1039/d0cp00453g

Kjær, C., Zhao, Y., Stockett, M. H., Chen, L., Hansen, K. & Nielsen, S. B. (2020). Gas-phase Förster resonance energy transfer in mass-selected ions with methylene or peptide linkers between two dyes: a concerted dance of charges. Physical Chemistry Chemical Physics, 22(19), 11095-11100. https://doi.org/10.1039/d0cp01287d

Petersen, A. U., Kjær, C., Jensen, C., Brøndsted Nielsen, M. & Brøndsted Nielsen, S. (2020). Gas-Phase Ion Fluorescence Spectroscopy of Tailor-made Rhodamine Homo- and Heterodyads: Quenching of Electronic Communication by π-Conjugated Linkers. Angewandte Chemie - International Edition, 59(47), 20946-20955. https://doi.org/10.1002/anie.202008314

Jones, N. C., Nielsen, S. B. & Hoffmann, S. V. (2020). On the delocalization length in RNA single strands of cytosine: how many bases see the light? Physical Chemistry Chemical Physics, 22(4), 2188-2192. https://doi.org/10.1039/c9cp05292e

Stockett, M. H., Kjær, C., Daly, S., Bieske, E. J., Verlet, J. R. R., Nielsen, S. B. & Bull, J. N. (2020). Photophysics of Isolated Rose Bengal Anions. The journal of physical chemistry. A, 124(41), 8429-8438. https://doi.org/10.1021/acs.jpca.0c07123

Gruber, E., Kjær, C., Nielsen, S. B. & Andersen, L. H. (2019). Intrinsic Photophysics of Light-harvesting Charge-tagged Chlorophyll a and b Pigments. Chemistry - A European Journal, 25(39), 9153-9158. https://doi.org/10.1002/chem.201901786

Sørensen, C. K. & Nielsen, S. B. (2019). Luminescence spectroscopy of oxazine dye cations isolated in vacuo. Physical Chemistry Chemical Physics, 21(8), 4600-4605. https://doi.org/10.1039/c8cp07340f

Kjær, C., Lissau, H., Gravesen Salinas, N. K., Østergaard Madsen, A., Stockett, M. H., Storm, F. E., Holm Hansen, T., Andersen, J. U., Laursen, B. W., Mikkelsen, K. V., Brøndsted Nielsen, M. & Brøndsted Nielsen, S. (2019). Luminescence Spectroscopy of Rhodamine Homodimer Dications in Vacuo Reveals Strong Dye-Dye Interactions. ChemPhysChem, 20(4), 533-537. https://doi.org/10.1002/cphc.201800933

Hansen, K., Sundén, A. E. K., Støchkel, K., Nielsen, S. B. & Dynefors, B. (2019). Non-scrambling of hydrogen in NH₄⁺(H₂O)₃ clusters. RSC Advances, 9(12), 6620-6626. https://doi.org/10.1039/c8ra10515d

Giacomozzi, L., Kjaer, C., Knudsen, J. L., Andersen, L. H., Nielsen, S. B. & Stockett, M. H. (2018). Absorption and luminescence spectroscopy of mass-selected flavin adenine dinucleotide mono-anions. Journal of Chemical Physics, 148(21), Artikel 214309. https://doi.org/10.1063/1.5024028

Toker, Y., Langeland, J., Gruber, E., Kjaer, C., Nielsen, S. B., Andersen, L. H., Bonin, V. A. & Schapiro, I. (2018). Counterion-controlled spectral tuning of the protonated Schiff-base retinal. Physical Review A, 98(4), Artikel 043428. https://doi.org/10.1103/PhysRevA.98.043428

Kjaer, C., Lisy, J. M. & Nielsen, S. B. (2018). Gas-Phase Ion Spectroscopy of Congo Red Dianions and Their Complexes with Betaine. Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory, 122(12), 3211-3217. https://doi.org/10.1021/acs.jpca.8b00904

Pedersen, B. & Nielsen, S. B. (2018). Gas-phase Ion Spectroscopy of Flexible and Nonflexible Nitrophenolates: Effect of Locking the Two Phenyl Units in 4’-nitro-[1,1’-biphenyl]-4-olate by a Bridging Atom. Journal of Self-Assembly and Molecular Electronics, 6, 1-12. Artikel 1. https://doi.org/10.13052/jsame2245-4551.6.001

Sunden, A. E. K., Stochkel, K., Hvelplund, P., Nielsen, S. B., Dynefors, B. & Hansen, K. (2018). Stabilities of protonated water-ammonia clusters. Journal of Chemical Physics, 148(18), Artikel 184306. https://doi.org/10.1063/1.5023620

Langeland, J., Kjær, C., Andersen, L. H. & Brøndsted Nielsen, S. (2018). The Effect of an Electric Field on the Spectroscopic Properties of the Isolated Green Fluorescent Protein Chromophore Anion. ChemPhysChem, 19(14), 1686-1690. https://doi.org/10.1002/cphc.201800225

Stockett, M. H., Boesen, M., Houmoller, J. & Nielsen, S. B. (2017). Accessing the Intrinsic Nature of Electronic Transitions from Gas-Phase Spectroscopy of Molecular Ion/Zwitterion Complexes. Angewandte Chemie International Edition, 56(13), 3490-3495. https://doi.org/10.1002/anie.201611320

Hansen, K., Byskov, C. S. & Nielsen, S. B. (2017). Energy flow in peptides after UV photoexcitation of backbone linkages. Physical Chemistry Chemical Physics, 19(30), 19640-19645. https://doi.org/10.1039/c7cp01768e

Stockett, M. H., Kjaer, C., Linder, M. K., Detty, M. R. & Nielsen, S. B. (2017). Luminescence spectroscopy of chalcogen substituted rhodamine cations in vacuo. Photochemical & Photobiological Sciences, 16(5), 779-784. https://doi.org/10.1039/c7pp00049a

Kjaer, C., Nielsen, S. B. & Stockett, M. H. (2017). Sibling rivalry: intrinsic luminescence from two xanthene dye monoanions, resorufin and fluorescein, provides evidence for excited-state proton transfer in the latter. Physical Chemistry Chemical Physics, 19(36), 24440-24444. https://doi.org/10.1039/c7cp04689h

Stockett, M. H., Houmøller, J., Støchkel, K., Svendsen, A. & Brøndsted Nielsen, S. (2016). A cylindrical quadrupole ion trap in combination with an electrospray ion source for gas-phase luminescence and absorption spectroscopy. Review of Scientific Instruments, 87(5), Artikel 053103. https://doi.org/10.1063/1.4948316

Stockett, M. H., Houmoller, J. & Nielsen, S. B. (2016). Nile blue shows its true colors in gas-phase absorption and luminescence ion spectroscopy. Journal of Chemical Physics, 145(10), Artikel 104303. https://doi.org/10.1063/1.4962364

Milne, B. F., Kjaer, C., Houmøller, J., Stockett, M. H., Toker, Y., Rubio, A. & Nielsen, S. B. (2016). On the Exciton Coupling between Two Chlorophyll Pigments in the Absence of a Protein Environment: Intrinsic Effects Revealed by Theory and Experiment. Angewandte Chemie International Edition, 55(21), 6248-51. https://doi.org/10.1002/anie.201601979

Madsen, M. M., Jones, N. C., Nielsen, S. B. & Hoffmann, S. V. (2016). On the wavelength dependence of UV induced thymine photolesions: A Synchrotron Radiation Circular Dichroism study. Physical Chemistry Chemical Physics, 18, 30436-30443. https://doi.org/10.1039/C6CP05980E

Kjaer, C., Stockett, M. H., Pedersen, B. M. & Nielsen, S. B. (2016). Strong Impact of an Axial Ligand on the Absorption by Chlorophyll a and b Pigments Determined by Gas-Phase Ion Spectroscopy Experiments. The Journal of Physical Chemistry Part B, 120(47), 12105-12110. https://doi.org/10.1021/acs.jpcb.6b10547